Co-reporter:Wei Zhang;Ruinian Hua;Xiaohui Qi;Jun Zhao;Lizhong Qin
CrystEngComm (1999-Present) 2017 vol. 19(Issue 35) pp:5214-5222
Publication Date(Web):2017/09/11
DOI:10.1039/C7CE01054K
Ce3+ and Tb3+ co-doped SrAlF5 nanorods were synthesized via a mild hydrothermal method. The XRD results show that the prepared samples are single-phase. FE-SEM reveals the high uniformity of the as-synthesized nanorods (∼1 μm in length and ∼50 nm in diameter). The effect of reaction conditions on the morphology of SrAlF5 was studied. When excited at 254 nm, contrasting weak emission signals of SrAlF5:Tb3+ were observed, while SrAlF5:Ce3+,Tb3+ nanorods exhibited the strong green emission of Tb3+ ions. The energy transfer between Ce3+ and Tb3+ was observed and studied. The mechanism of energy transfer was deduced to be the electric dipole–dipole interaction in the SrAlF5 host. The optimum doping concentration of Ce3+ ions is 7 mol% in SrAlF5:0.01Tb3+. The fluorescence decay curves for Ce3+ and Tb3+ of SrAlF5:Ce3+,Tb3+ nanorods were measured at room temperature. The lifetime of Ce3+ is in the range from 78.6 to 1.2 ns and the lifetime of Tb3+ varies from 4.39 to 7.39 ms. The energy transfer efficiency from Ce3+ to Tb3+ was calculated using lifetime and emission spectra. The chromaticity coordinates of all the samples were calculated and the chromaticity coordinates of SrAlF5:0.06Ce3+,0.01Tb3+ are very near those of the European broadcasting union (EBU) primary green color (0.29, 0.60).
Co-reporter:Ai Hongru;Li Xiangqin;Shi Shuyan;Zhang Ying;Liu Tianqing
RSC Advances (2011-Present) 2017 vol. 7(Issue 12) pp:7052-7059
Publication Date(Web):2017/01/20
DOI:10.1039/C6RA26897H
The Wenzel roughness factor r is one of the most important parameters to characterize a super-hydrophobic surface. In this study, in order to prove the feasibility of using laser scanning confocal microscopy (LSCM) to measure the roughness factor r, the detected r values by LSCM on texture-regular surfaces were compared with those calculated firstly, and then the r values measured by LSCM for texture-irregular rough surfaces were compared with those measured by AFM. The results show that the r values of texture-regular surfaces measured by LSCM are close to those calculated, and the LSCM measured r values of texture-irregular surfaces with small roughness are consistent with those measured by AFM. Moreover, the r values of texture-irregular surfaces with large roughness can only be measured by LSCM, the detected r values of three such super-hydrophobic surfaces are 2.13 ± 0.01, 2.12 ± 0.01 and 2.13 ± 0.02, respectively. In addition, it is proved that the r measured by LSCM as a line length ratio is equal to the original definition of roughness factor as the ratio of actual area of solid surface to the horizontal projected area. Consequently, it is reliable to measure the r value of a texture-irregular surface with large roughness in micro or submicro scale by LSCM.
Co-reporter:Kedong Song, liying Li, Xinyu Yan, Wen Zhang, Yu Zhang, Yiwei Wang, Tianqing Liu
Materials Science and Engineering: C 2017 Volume 70(Part 1) pp:231-240
Publication Date(Web):1 January 2017
DOI:10.1016/j.msec.2016.08.085
•The hydrogel scaffold was produced using chitosan, β-glycerophosphate and collagen.•This novel hydrogel is in liquid phase at low temperature and is gelatinized at 37 °C.•The new hydrogel provides ADSCs a favorable 3D environment with highly maintenance of proliferation and cytoactive.•ADSCs seeded hydrogel differentiated into adipose tissue, indicating favorable ability of adipogenesis.•This attractive property of C/GP/CO hydrogel points to its value as an excellent scaffold for tissue engineering.In this study, the interaction of human adipose tissue-derived stem cells (ADSCs) with chitosan/β-glycerophosphate/collagen (C/GP/Co) hybrid hydrogel was test, followed by investigating the capability of engineered adipose tissue formation using this ADSCs seeded hydrogel. The ADSCs were harvested and mixed with a C/GP/Co hydrogel followed by a gelation at 37 °C and an in vitro culture. The results showed that the ADSCs within C/GP/Co hydrogels achieved a 30% of expansion over 7 days in culture medium and encapsulated cell in C/GP/Co hydrogel demonstrated a characteristic morphology with high viability over 5 days. C/GP/Co hydrogel were subcutaneous injected into SD-rats to assess the biocompatibility. The induced ADSCs-C/GP/Co hydrogel and non-induced ADSCs-C/GP/Co hydrogel were subcutaneously injected into nude mice for detecting potential of adipogenic differentiation. It has shown that C/GP/Co hydrogel were well tolerated in SD rats where they had persisted over 4 weeks post implantation. Histology analysis indicated that induced ADSCs-C/GP/Co hydrogel has a greater number of adipocytes and vascularized adipose tissues compared with non-induced ADSCs-C/GP/Co hydrogel.
Co-reporter:Yanxia Zhu;Kedong Song;Siyu Jiang
Applied Biochemistry and Biotechnology 2017 Volume 181( Issue 1) pp:250-266
Publication Date(Web):2017 January
DOI:10.1007/s12010-016-2210-9
Cartilage tissue engineering is believed to provide effective cartilage repair post-injuries or diseases. Biomedical materials play a key role in achieving successful culture and fabrication of cartilage. The physical properties of a chitosan/gelatin hybrid hydrogel scaffold make it an ideal cartilage biomimetic material. In this study, a chitosan/gelatin hybrid hydrogel was chosen to fabricate a tissue-engineered cartilage in vitro by inoculating human adipose-derived stem cells (ADSCs) at both dynamic and traditional static culture conditions. A bioreactor that provides a dynamic culture condition has received greater applications in tissue engineering due to its optimal mass transfer efficiency and its ability to simulate an equivalent physical environment compared to human body. In this study, prior to cell-scaffold fabrication experiment, mathematical simulations were confirmed with a mass transfer of glucose and TGF-β2 both in rotating wall vessel bioreactor (RWVB) and static culture conditions in early stage of culture via computational fluid dynamic (CFD) method. To further investigate the feasibility of the mass transfer efficiency of the bioreactor, this RWVB was adopted to fabricate three-dimensional cell-hydrogel cartilage constructs in a dynamic environment. The results showed that the mass transfer efficiency of RWVB was faster in achieving a final equilibrium compared to culture in static culture conditions. ADSCs culturing in RWVB expanded three times more compared to that in static condition over 10 days. Induced cell cultivation in a dynamic RWVB showed extensive expression of extracellular matrix, while the cell distribution was found much more uniformly distributing with full infiltration of extracellular matrix inside the porous scaffold. The increased mass transfer efficiency of glucose and TGF-β2 from RWVB promoted cellular proliferation and chondrogenic differentiation of ADSCs inside chitosan/gelatin hybrid hydrogel scaffolds. The improved mass transfer also accelerated a dynamic fabrication of cell-hydrogel constructs, providing an alternative method in tissue engineering cartilage.
Co-reporter:Yanjie Li, Xiangqin Li, Wei Sun, Tianqing Liu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2017 Volume 518(Volume 518) pp:
Publication Date(Web):5 April 2017
DOI:10.1016/j.colsurfa.2017.01.040
•A mathematical model was developed to descript the mechanism of shape evolution and wetting transition during droplet evaporation process.•The driving force to depin the three phase contact line was derived by calculating the gradient of interface free energy.•The wetting transition of a Cassie droplet to Wenzel state during evaporation was determined.A model about the shape evolution and wetting transition of a droplet on superhydrophobic surfaces during evaporation was founded through analyzing the driving force and resistance on the three phase contact line (TPCL) of the droplet. The driving force to shift the TPCL was derived by calculating the gradient of interface free energy and the resistance was based on adhesion. The calculation results show that the volume reduction process of a droplet will undergo several stages. The first one is the constant contact line (CCL) stage with the resistance on TPCL larger than driving force. The second period is the constant contact angle (CCA) stage when the driving force is greater than the resistance. Later, the TPCL will move down along micro pillars until the substrate is wetted and the wetting transition is completed. Then, the drop will experience another CCL period before entering into the mixed mode stage. The evolution of droplet on micro/nano hierarchical surfaces is similar to that on micro structure surfaces, but with shorter CCL stage and without obvious contact angle reduction after the wetting transition because only micro structure is wetted. Finally, the reasonable agreement between the model and experimental results has been illustrated.Download high-res image (140KB)Download full-size image
Co-reporter:Kedong Song, Yanfei Yang, Lili Xu, Jiaxin Tian, Jiangli Fan, Zeren Jiao, Shihao Feng, Hong Wang, Yiwei Wang, Ling Wang, Tianqing Liu
Materials Science and Engineering: C 2016 Volume 62() pp:787-794
Publication Date(Web):1 May 2016
DOI:10.1016/j.msec.2016.02.036
•This study introduces a promising method for encapsulating ADSCs within hybrid gel-beads.•The gel-beads embedded with bone power provide a better biocompatible environment to mimic an in-vivo niche.•A spinner flask with a simple configuration was adopted to provide a dynamic condition for biomechanical stimuli.•Shear stress stimuli and bone powder were paramount to promote the cell differentiation and maturation of ADSCs.•This feasible approach was believed to fabricate engineered bone aggregates encapsulated by shape-adaptable gel-beads.Traditional treatment for bone diseases limits their clinical application due to undesirable host immune rejection, limited donator sources and severe pain and suffering for patients. Bone tissue engineering therefore is expected to be a more effective way in treating bone diseases. In the present study, hybrid calcium alginate/bone powder gel-beads with a uniform size distribution, good biocompatibility and osteoinductive capability, were prepared to be used as an in-vitro niche-like matrix. The beads were optimized using 2.5% (w/v) sodium alginate solution, 4.5% (w/v) CaCl2 solution and 5.0 mg/mL bone powder using an easy-to-use method. Human ADSCs were cultured and induced into chondrocytes and osteoblasts, respectively. The cells were characterized by histological staining showing the ADSCs were able to maintain their characteristic morphology with multipotent differentiation ability. ADSCs at density of 5 × 106 cells/mL were encapsulated into the gel-beads aiming to explore cell expansion under different conditions and the osteogenic induction of ADSCs was verified by specific staining. Results demonstrated that the encapsulated ADSCs expanded 5.6 folds in 10 days under dynamic condition via spinner flask, and were able to differentiate into osteoblasts (OBs) with extensive mineralized nodules forming the bone aggregates over 3 weeks postosteogenic induction. In summary, hybrid gel-beads encapsulating ADSCs are proved to be feasible as a new method to fabricate tissue engineered bone aggregation with potential to treat skeletal injury in the near future.
Co-reporter:Kedong Song, Yanfei Yang, Shuang Wu, Yu Zhang, Shihao Feng, Hong Wang, Yiwei Wang, Ling Wang, Tianqing Liu
Materials Science and Engineering: C 2016 Volume 58() pp:324-330
Publication Date(Web):1 January 2016
DOI:10.1016/j.msec.2015.08.033
•P(NIPAAm-co-HPM) grafted onto microcarrier for producing a novel thermosensitive microcarrier•Grafted microcarriers are biocompatible to significantly enhance adhesion and growth of BMMSCs.•Well attached BMMSCs could be mostly removed from grafted microcarrier with high cell viability.•This study presents a feasible substitute for cell recovery and a 3D condition for cell growth.•This study makes it convenient and efficient to expand cells by combining a dynamic bioreactor.Traditional two-dimensional (2D) static culture environment for stem cells followed by enzymatic cell detachment or mechanical treatment is routinely used in research laboratories. However, this method is not ideal as stem cells expand slowly, with cell damage and partial loss of specific stemness. For this reason, a better culture condition is urgently needed to improve stem cell recovery. A novel thermosensitive P(NIPAAm-co-HPM)-g-TMSPM-g-microcarrier was prepared here as a three-dimensional (3D) culture substitute. This novel microcarrier was prepared by grafting NIPAAm and HPM to the surface of glass microcarrier using TMSPM through surface free radical copolymerization. The prepared material was tested in cell culture and via cooling harvest method. We found that NIPAAm was successfully grafted on to the surface of the microcarriers, providing an excellent biocompatible environment for BMMSC adhesion and growth. More importantly, BMMSCs could be fully removed from the thermosensitive glass microcarriers with remained cell viability.
Co-reporter:Meiling Zhuang, Tianqing Liu, Kedong Song, Dan Ge, Xiangqin Li
Materials Science and Engineering: C 2015 Volume 55() pp:410-419
Publication Date(Web):1 October 2015
DOI:10.1016/j.msec.2015.05.040
•PNIPAAm-grafted HFMs exhibited thermoresponsive characteristic.•The OB cells could adhere and spread well on the surface of PNIPAAm-grafted HFMs.•PNIPAAm-grafted HFMs do not significantly impact ALP activity and OCN protein expression level of OB cells.•Cell could be detached from PNIPAAm-grafted HFMs when temperature decreased from 37 °C to 20 °C.Hollow fiber membrane (HFM) culture system is one of the most important bioreactors for the large-scale culture and expansion of therapeutic cells. However, enzymatic and mechanical treatments are traditionally applied to harvest the expanded cells from HFMs, which inevitably causes harm to the cells. In this study, thermo-responsive cellulose acetate HFMs for cell culture and non-invasive harvest were prepared for the first time via free radical polymerization in the presence of cerium (IV). ATR-FTIR and elemental analysis results indicated that the poly(N-isopropylacrylamide) (PNIPAAm) was covalently grafted on HFMs successfully. Dynamic contact angle measurements at different temperatures revealed that the magnitude of volume phase transition was decreased with increasing grafted amount of PNIPAAm. And the amount of serum protein adsorbed on HFMs surface also displayed the same pattern. Meanwhile osteoblasts adhered and spread well on the surface of PNIPAAm-grafted HFMs at 37 °C. And Calcein-AM/PI staining, AB assay, ALP activity and OCN protein expression level all showed that PNIPAAm-grafted HFMs had good cell compatibility. After incubation at 20 °C for 120 min, the adhering cells on PNIPAAm-grafted HFMs turned to be round and detached after being gently pipetted. These results suggest that thermo-responsive HFMs are attractive cell culture substrates which enable cell culture, expansion and the recovery without proteolytic enzyme treatment for the application in tissue engineering and regenerative medicine.
Co-reporter:Kedong Song;Xinyu Yan;Yu Zhang;Fei Song
Bioprocess and Biosystems Engineering 2015 Volume 38( Issue 8) pp:1527-1540
Publication Date(Web):2015 August
DOI:10.1007/s00449-015-1395-6
Currently, RWVB (Rotating wall vessel bioreactor) combined with a microcarrier used for in vitro expansion revealed that the suspended cells attached on the microcarrier will collide with outer and inner cylinders of RWVB inevitably, which leads to harmful results to the cells. Considering this, hollow fiber (HF) membrane module treated as a cell carrier is adopted to combine with RWVB to form a novel rotating wall hollow fiber membrane bioreactor (RWHMB) to avoid aforementioned harmful collision, since the cells cultured inside
this bioreactor will mainly adhere to large specific surface of hollow fiber membrane module. Prior to cell experiment, mathematical simulations concerned with flow field inside RWHMB are performed by CFD, which includes the distributions of the total pressure, velocity, and shear stress with the variation of rotating speeds and directions, as well as the radial location and diameter of hollow fiber membrane. To further confirm the feasible parameters getting from the simulation, this RWHMB is adopted to expand osteoblasts isolated from SD rats within its dynamic conditions. Cell expansion in T-flask is carried out as a negative control. The results showed that with the same rotating direction and speed of 10 rpm, inner and outer cylinders of RWHMB generated cyclical stress stimulus, which was acceptable to cell expansion and facilitated the secretion of extracellular matrix. Besides, hollow fiber membrane carrier with a diameter of 0.2 mm has an excellent biocompatibility and their radial locations presented a tiny influence on flow field inside the culture chamber.
Co-reporter:Kedong Song, Liying Li, Wenfang Li, Yanxia Zhu, Zeren Jiao, Mayasari Lim, Meiyun Fang, Fangxin Shi, Ling Wang, Tianqing Liu
Materials Science and Engineering: C 2015 Volume 55() pp:384-392
Publication Date(Web):1 October 2015
DOI:10.1016/j.msec.2015.05.062
•ADSCs/hybrid scaffold constructs are dynamically fabricated in a spinner flask with a special framework.•Inside convection in spinner flask made enough supplement of oxygen and nutrients far beyond the depth of passive diffusion.•3D culture environment accelerated mass transfer of nutrients and discharge of metabolites.•A special designed steel framework successfully avoided the collision between constructs and walls.Cartilage transplantation using in vitro tissue engineered cartilage is considered a promising treatment for articular cartilage defects. In this study, we assessed the advantages of adipose derived stem cells (ADSCs) combined with chitosan/gelatin hybrid hydrogel scaffolds, which acted as a cartilage biomimetic scaffold, to fabricate a tissue engineered cartilage dynamically in vitro and compared this with traditional static culture. Physical properties of the hydrogel scaffolds were evaluated and ADSCs were inoculated into the hydrogel at a density of 1 × 107 cells/mL and cultured in a spinner flask with a special designed steel framework and feed with chondrogenic inductive media for two weeks. The results showed that the average pore size, porosity, swelling rate and elasticity modulus of hybrid scaffolds with good biocompatibility were 118.25 ± 19.51 μm, 82.60 ± 2.34%, 361.28 ± 0.47% and 61.2 ± 0.16 kPa, respectively. ADSCs grew well in chitosan/gelatin hybrid scaffold and successfully differentiated into chondrocytes, showing that the scaffolds were suitable for tissue engineering applications in cartilage regeneration. Induced cells cultivated in a dynamic spinner flask with a special designed steel frame expressed more proteoglycans and the cell distribution was much more uniform with the scaffold being filled mostly with extracellular matrix produced by cells. A spinner flask with framework promoted proliferation and chondrogenic differentiation of ADSCs within chitosan/gelatin hybrid scaffolds and accelerated dynamic fabrication of cell–hydrogel constructs, which could be a selective and good method to construct tissue engineered cartilage in vitro.
Co-reporter:Kedong Song;Dan Ge;Shui Guan;Chenggong Sun
Applied Biochemistry and Biotechnology 2014 Volume 174( Issue 6) pp:2114-2130
Publication Date(Web):2014 November
DOI:10.1007/s12010-014-1165-y
The aim of this study is to analyze the growth and substance metabolism of neural stem cells (NSCs) cultured in biological collagen-based scaffolds. Mass transfer and metabolism model of glucose, lactic acid, and dissolved oxygen (DO) were established and solved on MATLAB platform to obtain the concentration distributions of DO, glucose, and lactic acid in culture system, respectively. Calculation results showed that the DO influenced their normal growth and metabolism of NSCs mostly in the in vitro culture within collagen-based scaffolds. This study also confirmed that 2-mm thickness of collagen scaffold was capable of in vitro cultivation and growth of NSCs with an inoculating density of 1 × 106 cells/mL.
Co-reporter:Song Kedong;Li Wenfang;Zhu Yanxia;Wang Hong
Applied Biochemistry and Biotechnology 2014 Volume 174( Issue 4) pp:1331-1343
Publication Date(Web):2014 October
DOI:10.1007/s12010-014-1132-7
The in vitro dynamic fabrications of tissue-engineered bones were performed to assess the advantages of human adipose-derived stem cells (hADSCs) combined with acellular cancellous bone scaffold coming from fresh pig femur in a spinner flask compared with traditional static culture. In this study, the bio-derived cancellous bone was regarded as a biomimetic scaffold, and its surface appearance was observed under scanning electron microscopy (SEM). Moreover, its modulus of elasticity and chemical composition were measured with universal testing machine (UTM) and infrared detector, respectively. hADSCs were inoculated into cancellous bone scaffold at a density of 1 × 106 cells/mL and cultured in spinner flask and T-flask with osteogenic medium (OM) for 2 weeks, respectively. Following to this, the osteogenic differentiation was qualitatively and quantitatively detected with alkaline phosphatase (ALP) kits, and the cell growth and viability were assayed using Live/Dead staining; cell adhesion and extracellular matrix secretion were observed under a SEM. The average pore size of cancellous bone scaffold was 284.5 ± 83.62 μm, the elasticity modulus was 41.27 ± 15.63 MPa, and it also showed excellent biocompatibility. The hADSCs with multidifferentiation potentials were well proliferated, could grow to 90 % fusion within 5 days, and were therefore suitable to use as seed cells in the construction of tissue-engineered bones. After 2 weeks of fabrication, cells were well-distributed on scaffolds, and these scaffolds still remained intact. Compared to static environment, the ALP expression, cell distribution, and extracellular matrix secretion on cancellous bones in spinner flask were much better. It confirmed that three-dimensional dynamic culture in spinner flask promoted ADSC osteogenic differentiation, proliferation, and matrix secretion significantly to make for the fabrication of engineered bone substitutes.
Co-reporter:Kedong Song;Liying Li;Ruipeng Li;Mayasari Lim
Applied Biochemistry and Biotechnology 2014 Volume 173( Issue 3) pp:838-850
Publication Date(Web):2014 June
DOI:10.1007/s12010-014-0874-6
The Ca-alginate/gelatin (CAG) microbeads were prepared and evaluated through assays for their mechanical strength, permeability, and the feasibility as a cell carrier for in vitro culture of neural stem cells. The effects of different concentrations of sodium alginate, gelatin, and calcium chloride on the mechanical strength of CAG microbeads were determined using a self-made puncture force tester. Following this, the microbeads were immersed in DMEM media for a specified period to test its decay resistance. A diffusion model including a calculation formula of diffusion coefficient was built to investigate the diffusion of glucose and bovine serum albumin (BSA) through the wall of the microbeads. Furthermore, the feasibility of the microbeads for in vitro culture was identified using neural stem cells from Kunming mouse. Through a systematic approach and comprehensive analysis, the optimal gelatin conditions for microbead preparation were determined; the final combination of parameters of 1.5 % (wt%) sodium alginate (SA), 0.5 % (wt%) gelatin, and 4 % (wt%) CaCl2 were the best conditions for NSC cultures. This experiment demonstrated that CAG microbeads had good cytocompatibility that made it suitable for the culture and successfully maintained stemness of neural stem cells.
Co-reporter:Kedong Song, Yanfei Yang, Shixiao Li, Meiling Wu, Yixing Wu, Mayasari Lim, Tianqing Liu
Materials Science and Engineering: C 2014 40() pp: 197-203
Publication Date(Web):
DOI:10.1016/j.msec.2014.03.028
Co-reporter:Tianqing Liu, Wei Sun, Xiangqin Li, Xiangyu Sun and Hongru Ai
Soft Matter 2013 vol. 9(Issue 41) pp:9807-9815
Publication Date(Web):30 Aug 2013
DOI:10.1039/C3SM51762D
Condensed droplets on different nano-textured surfaces may appear in three distinct wetting states, the Cassie–Baxter state with composite wetting, Wenzel state with complete wetting, and the partially wetted (PW) state. To maintain the super-hydrophobicity of a textured surface, condensed drops on it are usually expected to be in a Cassie–Baxter or PW state. Therefore, it is of importance to clarify the relation between condensed droplet wetting states and the nano-pillar geometries of surfaces. In view of the fact that all condensed droplets in diverse wetting states originate from the nuclei and/or condensate spots growing along different pathways, we think that the distinct growth modes of a condensate correspond to different energy increasing rates (EIRs), and a condensed drop should grow along the route with the minimum EIR. In this paper, accordingly, the EIRs of a droplet on different textured surfaces were analyzed during its growth along three pathways. The results show that the smallest initial EIR of a condensate spot occurs in the increasing contact angel (CA) mode, so that it will grow with the CA enlarging and the base area initially remaining unchanged. Then the EIR of the increasing CA mode becomes much higher than that of the other two modes. The base area of the drop begins to enlarge while the CA remains unchanged. During this period, the increasing base area can be either in a wetted or composite state, resulting in a Wenzel or PW droplet forming, respectively. The growth mode and the wetting state of a condensed droplet are strongly related to the nano-structure of the surface. Additionally, the calculation results of this model are consistent with experimental observations in the literature for the wetting states of condensed drops on nano-textured surfaces, with an accuracy of 91.9%, which is higher than the accuracy of results calculated with previously reported formulas.
Co-reporter:Lei Yang;Kedong Song;Shuang Wu ;Xin Fan
Journal of Applied Polymer Science 2013 Volume 127( Issue 6) pp:4280-4287
Publication Date(Web):
DOI:10.1002/app.38035
Abstract
A novel copolymer, poly(N-isopropylacrylamide-co-hydroxypropyl methacrylate-co-3-trimethoxysilypropyl methacrylate) has been synthesized and the hydrodynamic diameters in various aqueous solutions under different temperatures are determined by dynamic light scattering. The results show that the hydrodynamic diameters of copolymers have no obvious change in each working solution below lower critical solution temperature (LCST); across LCST, the diameters increased suddenly at different initial temperature in various aqueous solutions; above LCST, they decreased slightly as the temperature increased in UHQ water, and increased continuously with increasing temperature or salt concentration in saline solutions, and reduced with the rising of pH value in pH buffer. These are attributed to different intermolecular and intramolecular forces leading to disparity in dimension, conformation, and LCST of copolymers. The hydrogen bonding between water molecules and copolymer chains could maintain size and conformation of copolymer single chain; the hydrogen bonding between amide linkages and hydrophobic interactions between isopropyl groups result in intramolecular collapse and intermolecular aggregation; the electrostatic repulsion weakens aggregation extent of copolymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Kedong Song, Yingchao Liu, Hugo M. Macedo, Lili Jiang, Chao Li, Guanyu Mei, Tianqing Liu
Materials Science and Engineering: C 2013 Volume 33(Issue 3) pp:1506-1513
Publication Date(Web):1 April 2013
DOI:10.1016/j.msec.2012.12.054
Nutrient depletion within three-dimensional (3D) scaffolds is one of the major hurdles in the use of this technology to grow cells for applications in tissue engineering. In order to help in addressing it, we herein propose to use the controlled release of encapsulated nutrients within polymer microspheres into chitosan-based 3D scaffolds, wherein the microspheres are embedded. This method has allowed maintaining a stable concentration of nutrients within the scaffolds over the long term. The polymer microspheres were prepared using multiple emulsions (w/o/w), in which bovine serum albumin (BSA) and poly (lactic-co-glycolic) acid (PLGA) were regarded as the protein pattern and the exoperidium material, respectively. These were then mixed with a chitosan solution in order to form the scaffolds by cryo-desiccation. The release of BSA, entrapped within the embedded microspheres, was monitored with time using a BCA kit. The morphology and structure of the PLGA microspheres containing BSA before and after embedding within the scaffold were observed under a scanning electron microscope (SEM). These had a round shape with diameters in the range of 27–55 μm, whereas the chitosan-based scaffolds had a uniform porous structure with the microspheres uniformly dispersed within their 3D structure and without any morphological change. In addition, the porosity, water absorption and degradation rate at 37 °C in an aqueous environment of 1% chitosan-based scaffolds were (92.99 ± 2.51) %, (89.66 ± 0.66) % and (73.77 ± 3.21) %, respectively. The studies of BSA release from the embedded microspheres have shown a sustained and cumulative tendency with little initial burst, with (20.24 ± 0.83) % of the initial amount released after 168 h (an average rate of 0.12%/h). The protein concentration within the chitosan-based scaffolds after 168 h was found to be (11.44 ± 1.81) × 10− 2 mg/mL. This novel chitosan-based scaffold embedded with PLGA microspheres has proven to be a promising technique for the development of new and improved tissue engineering scaffolds.Highlights► A novel method was shown to improve the diffusivity limitations of scaffolds. ► The incorporation of PLGA microspheres containing nutrients was prepared. ► These hybrid scaffolds were shown to have an improved release of nutrients.
Co-reporter:Kedong Song;Zhaomin Wang;Wenfang Li;Chao Zhang
Applied Biochemistry and Biotechnology 2013 Volume 170( Issue 2) pp:459-470
Publication Date(Web):2013 May
DOI:10.1007/s12010-013-0210-6
The in vitro basic biological characteristics and directed differentiation potential towards cardiomyocytes of adult adipose-derived stem cells (ADSCs) induced by angiotensin II were both investigated. ADSCs were isolated from adult adipose tissue and cultured in vitro, and were subsequently induced into adipocytes, chondrocytes, and osteoblasts for assays of multipotential differentiation. The morphological characteristics of ADSCs were observed under an inverted microscope in bright field and phase-contrast ways and a confocal laser scanning microscopy. Moreover, the directional differentiation potential was observed by Oil Red, alkaline phosphatase, von Kossa, and toluidine blue stainings, respectively. The expressions of CD34, CD44, CD45, CD105, and HLA-DR were also detected via flow cytometry. Following to this, ADSCs were induced by angiotensin II and basic fibroblast growth factor for the purpose of directional differentiation towards cardiomyocyte-like cells, and the cells treated with 5-azacytidine were regarded as the control. The results showed that the isolated and cultured ADSCs presented a typical morphology of fusiform shape and also expressed CD44, CD105, but not CD34, CD45, and HLA-DR with assays of flow cytometry. The multi-differentiations to adipocytes, chondrocytes, and osteoblasts confirmed that the isolated cells maintained the stem characteristics generating from adipose tissues. After 4 weeks of induction by angiotensin II, the cells expressed myosin heavy chain, troponin I, and connexin43 by immunocytochemistry staining, but without beating of the cells. This current study indicated that ADSCs possessed the characteristics of mesenchymal stem cells and angiotensin II could induce ADSCs into cardiomyocyte-like cells.
Co-reporter:Dan Ge;Kedong Song;Shui Guan;Yanli Qi;Bo Guan
Applied Biochemistry and Biotechnology 2013 Volume 170( Issue 2) pp:406-419
Publication Date(Web):2013 May
DOI:10.1007/s12010-013-0211-5
A stable and fast method for constructing a neural-like tissue from rat neural stem/progenitor cells (rNS/PCs) based on three-dimensional (3D) collagen gel is described. First step, the collagen-embedded rNS/PCs expanded with the medium consisting of DMEM/F12/RPMI1640 (1:1:1) supplemented with EGF and bFGF was used to expand the cells in gel in 96-well plates until the average diameter of cell clusters was about 50–100 μm with the cell density higher than 107 cells/mL. In the second step, the initial medium was replaced with NB/B-27 supplemented with bFGF and BDNF. The results show that cells in collagen presented neural-like morphology and maintained live cell rate around 82 % in neural network pattern at least for 42 days under static conditions. The cell–collagen constructs were detected by immunofluorescence and immunohistochemistry test after 42 days of culture, part of cells still maintained the character of rNS/PCs, and others differentiated into neurons, astrocytes, and oligodendrocytes. Our 3D neural-like tissue construct was similar to the neural tissue in morphology and cell compositions. They thus have a potential to be used for drug screening, detection of environment toxins, and replacement therapy.
Co-reporter:Kedong Song;Hai Wang;Bowen Zhang;Mayasari Lim
Cell Stress and Chaperones 2013 Volume 18( Issue 2) pp:193-201
Publication Date(Web):2013 March
DOI:10.1007/s12192-012-0370-2
In this paper, two-dimensional flow field simulation was conducted to determine shear stresses and velocity profiles for bone tissue engineering in a rotating wall vessel bioreactor (RWVB). In addition, in vitro three-dimensional fabrication of tissue-engineered bones was carried out in optimized bioreactor conditions, and in vivo implantation using fabricated bones was performed for segmental bone defects of Zelanian rabbits. The distribution of dynamic pressure, total pressure, shear stress, and velocity within the culture chamber was calculated for different scaffold locations. According to the simulation results, the dynamic pressure, velocity, and shear stress around the surface of cell-scaffold construction periodically changed at different locations of the RWVB, which could result in periodical stress stimulation for fabricated tissue constructs. However, overall shear stresses were relatively low, and the fluid velocities were uniform in the bioreactor. Our in vitro experiments showed that the number of cells cultured in the RWVB was five times higher than those cultured in a T-flask. The tissue-engineered bones grew very well in the RWVB. This study demonstrates that stress stimulation in an RWVB can be beneficial for cell/bio-derived bone constructs fabricated in an RWVB, with an application for repairing segmental bone defects.
Co-reporter:T.Q. Liu, W. Sun, X.Y. Sun, H.R. Ai
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 414() pp:366-374
Publication Date(Web):20 November 2012
DOI:10.1016/j.colsurfa.2012.08.063
The out-of-plane jumping motion of coalesced condensed drops on super-hydrophobic surfaces can potentially enhance dropwise condensation greatly. But the jumping mechanism is not clear. In this paper, the initial shape of a coalesced droplet is determined based on the conservation of drop interface free energy (IFE) and viscous dissipation energy before and after two or more condensed droplets merge. The coalesced drop is in unstable state with a driving force to reduce its base radius toward equilibrium state. Then, the driving force and resistance on three-phase contact line (TPCL) are analyzed during the drop transformation. And the dynamic equation describing the shape conversion of the droplet is proposed and solved. The jumping height of a merged drop is determined according to the up moving speed of drop gravity center when the base radius of the droplet reduces to 0. The calculation results show that a coalesced droplet on flat surface can transform its shape limitedly. It cannot jump since its transformation stops before it comes to its equilibrium state. A wetted drop on rough surfaces is even more difficult to transform and jump because of the greater TPCL resistance. However, on a two-tier surface, a partially wetted drop impaling only the micro-scale roughness exhibits a shape transition to Cassie state and possible jumping upon coalescence if the micro and nanostructure parameters are suitable. Furthermore, after the coalescence of two or more Cassie state drops with their scale range from tens micrometer to millimeter on a textured surface, the merged composite drop can easily transform until its base radius becomes 0 and then jumps. A too small or too large merged drop will not jump because the obvious viscous dissipation energy or drop gravity respectively dominates the behavior of the drop. Meanwhile the coalescence-induced jumping of two drops will also not take place if their scales are significantly different. It can be concluded that the key factors resulting in condensed drops jumping are the merged drop in unstable state with enough surplus IFE and small TPCL resistance on nano or micro–nano two-tier surfaces.Graphical abstractThe process of coalescence, transformation and jumping of two condensed micro-drops on super-hydrophobic surfaces was recorded and modeled.Highlights► Initial shape of a coalesced droplet is determined based on energy conservation. ► The driving force and resistance during drop transformation are analyzed. ► A dynamic equation describing shape conversion of a droplet is proposed and solved. ► Merged droplets jump because they are in unstable state on nanostructure surfaces.
Co-reporter:Kedong Song;Wenfang Li;Hong Wang;Hai Wang
Applied Biochemistry and Biotechnology 2012 Volume 167( Issue 8) pp:2381-2387
Publication Date(Web):2012 August
DOI:10.1007/s12010-012-9764-y
The purpose of this study was to evaluate the differentiation potential of human adipose-derived stem cells (hADSCs) into adipocytes by coculturing them with human mature adipocytes. The transwell culture system was utilized for indirect coculture of hADSCs and human mature adipocytes at four different hADSCs-to-mature adipocytes ratios, i.e., 1:5, 1:1, 2:1, and 5:1. After 8 days of coculture, the Oil Red O and Trypan Blue stainings were performed for the evaluation of adipogenic differentiation of hADSCs. In addition, flow cytometric analysis and Hoechst 33342/PI double staining were performed after 20 days of coculture. The Oil Red O and Trypan Blue stainings showed that hADSCs with high viability could not differentiate into mature adipocytes after 8 or 20 days of coculture. However, flow cytometric analysis indicated that CD105 expression of hADSCs decreased after 20 days of coculture. These results indicated that hADSCs cocultured with human adult adipocytes could not successfully differentiate into adipocytes.
Co-reporter:Lili Jiang;Kedong Song
Applied Biochemistry and Biotechnology 2012 Volume 168( Issue 8) pp:2230-2244
Publication Date(Web):2012 December
DOI:10.1007/s12010-012-9932-0
Abundant and less passaged cells are highly expected in clinical application since repeated subculture reduces stem cell characteristics. Long time culture of stem cells without passage is therefore needed. The growth and cell viability of human adipose-derived stem cells (hADSCs) were investigated by live/dead staining, cck-8 kits, and hemocytometer every day in 30 days of culture. The stem cell characteristics of hADSCs at the beginning and the end of culture were detected by flow cytometry and histochemical staining. hADSCs can be cultured up to the 30th day in one passage while maintaining high level cell viability and their stem cell characteristics. In addition, the cells displayed two plateau phases and three logarithmic phases during 1 month of culture. Increasing expression of cyclin A at protein level resulted in an increase in the percentage of hADSCs in the S and G2/M phases, while decreasing protein level of cyclin D1 induced a decline in the proportion of hADSCs in the G0/G1 phase, regulating cells to move into rapid proliferation. This study demonstrates that a great quantity of hADSCs can be obtained in vitro by prolonging the culture time of each passage. And cyclin A and cyclin D1 affect the distribution of cell cycle and regulate the growth of hADSCs.
Co-reporter:Kedong Song;Hai Wang;Hong Wang;Ling Wang
Applied Biochemistry and Biotechnology 2011 Volume 165( Issue 3-4) pp:776-784
Publication Date(Web):2011 October
DOI:10.1007/s12010-011-9295-y
The in vitro suitable action distance between umbilical cord blood-derived hematopoietic stem/progenitor cells and its feeder cell, human adipose-derived stem cells, during their co-culture, was investigated through a novel transwell co-culture protocol, in which the distance between the two culture chambers where each cell type is growing can be adjusted from 10 to 450 μm. The total cell number was determined with a hemacytometer, and the cell morphology was observed under an inverted microscope each day. After 7 days of co-culture, the fold-expansion, surface antigen expression of CD34+ and CFU-GM assay of the hematopoietic mononuclear cells (MNCs) were analyzed. The results showed that there was an optimal communication distance at around 350 μm between both types of stem cells during their in vitro co-culture. By using this distance, the UCB-MNCs and CD34+ cells were expanded by 15.1 ± 0.2 and 5.0 ± 0.1-fold, respectively. It can therefore be concluded that the optimal action distance between stem cells and their supportive cells, when cultured together for 7 days, is of around 350 μm.
Co-reporter:Kedong Song;Mo Qiao;Bo Jiang
Journal of Materials Science: Materials in Medicine 2010 Volume 21( Issue 10) pp:2835-2842
Publication Date(Web):2010 October
DOI:10.1007/s10856-010-4131-4
This paper introduces a novel type of injectable temperature-sensitive chitosan/glycerophosphate/collagen (C/GP/Co) hydrogel that possesses great biocompatibility for the culture of adipose tissue-derived stem cells. The C/GP/Co hydrogel is prepared by mixing 2.2% (v/v) chitosan with 50% (w/w) β-glycerophosphate at different proportions and afterwards adding 2 mg/ml of collagen. The gelation time of the prepared solution at 37°C was found to be of around 12 min. The inner structure of the hydrogel presented a porous spongy structure, as observed by scanning electron microscopy. Moreover, the osmolality of the medium in contact with the hydrogel was in the range of 310–330 mmol kg−1. These analyses have shown that the C/GP/Co hydrogels are structurally feasible for cell culture, while their biocompatibility was further examined. Human adipose tissue-derived stem cells (ADSCs) were seeded into the developed C/GP and C/GP/Co hydrogels (The ratios of C/GP and C/GP/Co were 5:1 and 5:1:6, respectively), and the cellular growth was periodically observed under an inverted microscope. The proliferation of ADSCs was detected using cck-8 kits, while cell apoptosis was determined by a Live/Dead Viability/Cytotoxicity kit. After 7 days of culture, cells within the C/GP/Co hydrogels displayed a typical adherent cell morphology and good proliferation with very high cellular viability. It was thus demonstrated that the novel C/GP/Co hydrogel herein described possess excellent cellular compatibility, representing a new alternative as a scaffold for tissue engineering, with the added advantage of being a gel at the body’s temperature that turns liquid at room temperature.
Co-reporter:Tianqing Liu, Wei Sun, Xiangyu Sun, and Hongru Ai
Langmuir 2010 Volume 26(Issue 18) pp:14835-14841
Publication Date(Web):August 23, 2010
DOI:10.1021/la101845t
Condensed drops usually display a Wenzel state on a superhydrophobic surface (SHS) only with microrough architecture, while Cassie drops easily appear on a surface with micro−nano hierarchical roughness. The mechanism of this is not very clear. It is important to understand how the hierarchical structure affects the states of condensation drops so that a good SHS can be designed to achieve the highly efficient dropwise condensation. In this study, the interface free energy (IFE) of a local condensate, which comes from the growth and combination of numerous initial condensation nuclei, was calculated during its shape changes from the early flat shape to a Wenzel or Cassie state. The final state of a condensed drop was determined by whether the IFE continuously decreased or a minimum value existed. The calculation results indicate that the condensation drops on the surface only with microroughness display a Wenzel state because the IFE curve of a condensed drop first decreases and then increases, existing at a minimum value corresponding to a Wenzel drop. On a surface with proper hierarchical roughness, however, the interface energy curve of a condensed drop will continuously decline until reaching a Cassie state. Therefore, a condensed drop on a hierarchical roughness surface can spontaneously change into a Cassie state. Besides, the states and apparent contact angles of condensed drops on a SHS with different structural parameters published in the literature were calculated and compared with experimental observations. The results show that the calculated condensed drop states are well-coordinated with experimental clarifications. We can conclude that micro−nano hierarchical roughness is the key structural factor for sustaining condensed drops in a Cassie state on a SHS.
Co-reporter:Song Kedong;Fan Xiubo;Liu Tianqing
Journal of Materials Science: Materials in Medicine 2010 Volume 21( Issue 12) pp:3183-3193
Publication Date(Web):2010 December
DOI:10.1007/s10856-010-4167-5
The simultaneous expansion and harvest of hematopoietic stem cells and mesenchymal stem cells derived from umbilical cord blood were carried out using bioreactors. The co-culture of umbilical cord blood (UCB)-derived hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) was performed within spinner flasks and a rotating wall vessel (RWV) bioreactor using glass-coated styrene copolymer (GCSC) microcarriers. The medium used was composed of serum-free IMDM containing a cocktail of SCF 15 ng·mL−1, FL 5 ng·mL−1, TPO 6 ng·mL−1, IL-3 15 ng·mL−1, G-CSF 1 ng·mL−1 and GM-CSF 5 ng·mL−1. Accessory stromal cells derived from normal allogeneic adipose tissue were encapsulated in alginate-chitosan (AC) beads and used as feeding cells. The quality of the harvested UCB-HSCs and MSCs was assessed by immunophenotype analysis, methylcellulose colony and multi-lineage differentiation assays. After 12 days of culture, the fold-expansion of total cell numbers, colony-forming units (CFU-C), CD34+/CD45+/CD105− (HSCs) cells and CD34−/CD45−/CD105+ (MSCs) cells using the RWV bioreactor were (3.7 ± 0.3)- , (5.1 ± 1.2)- , (5.2 ± 0.4)- , and (13.9 ± 1.2)-fold respectively, significantly better than those obtained using spinner flasks. Moreover, UCB-HSCs and UCB-MSCs could be easily separated by gravity sedimentation after the co-culture period as only UCB-MSCs adhered on to the microcarriers. Simultaneously, we found that the fibroblast-like cells growing on the surface of the GCSC microcarriers could be induced and differentiated towards the osteoblastic, chondrocytic and adipocytic lineages. Phenotypically, these cells were very similarly to the MSCs derived from bone marrow positively expressing the MSCs-related markers CD13, CD44, CD73 and CD105, while negatively expressing the HSCs-related markers CD34, CD45 and HLA-DR. It was thus demonstrated that the simultaneous expansion and harvest of UCB-HSCs and UCB-MSCs is possible to be accomplished using a feasible bioreactor culture system such as the RWV bioreactor with the support of GCSC microcarriers.
Co-reporter:Kedong Song;Guofeng Zhao;Lei Zhang;Xuehu Ma
Biotechnology Letters 2009 Volume 31( Issue 7) pp:
Publication Date(Web):2009 July
DOI:10.1007/s10529-009-9961-0
The expansion of hematopoietic stem/progenitor cells (HSPCs) from umbilical cord blood (UCB) with the support of microencapsulated osteoblasts under hypoxia environment was investigated. The expansion of HSPCs was evaluated through the total number of UCB mononuclear cells (MNCs) produced, their repopulating potential with the colony-forming unit assay (CFU-Cs) and CD34+ phenotypic analysis with flow cytometry. At the end of 7 days of culture, the UCB-MNCs, CFU-Cs and CD34+ cells had achieved 18.7 ± 1.6, 11.6 ± 0.9 and 23.4 ± 2-fold expansions, respectively, in the test groups. These were significantly different from those in control groups. Microencapsulated osteoblasts under hypoxia conditions had therefore a significant effect on the expansion potential of HSPCs in vitro.
Co-reporter:Han Wang;Tian-Qing Liu;Yan-Xia Zhu;Shui Guan
Molecular and Cellular Biochemistry 2009 Volume 330( Issue 1-2) pp:
Publication Date(Web):2009 October
DOI:10.1007/s11010-009-0099-0
The effect of protocatechuic acid (PCA) from Alpinia oxyphylla and catapol from Rehmannia on the proliferation capacity of human adipose tissue-derived stromal cells (hADSCs) was investigated in vitro. Cell counts showed that treatment of hADSCs with PCA for 48 h increased the cell number in a dose-dependent manner, while no obvious effect of catapol on the proliferation of hADSCs was observed. In addition, the cell number of hADSCs treated by 1.5 mM PCA increased in a time-dependent manner. The flow cytometric analysis of DNA content demonstrated the cell cycle progress from the G0/G1 phase to the S phase. Western blot analysis revealed the elevated expression of cyclin D1 in hADSCs induced by PCA treatment. Cyclin D1-siRNA transfection significantly inhibit the promotion of cell proliferation by PCA. Furthermore, the flow cytometric analysis of the cell surface antigens and the multidifferential potential tests of PCA-treated hADSCs showed that the cells retained their functional characteristics of multipotential mesenchymal progenitors. It is concluded that PCA can effectively up-regulate the proliferation of hADSCs.
Co-reporter:Yanxia Zhu;Kedong Song;Ruiming Ning
Molecular and Cellular Biochemistry 2009 Volume 324( Issue 1-2) pp:117-129
Publication Date(Web):2009 April
DOI:10.1007/s11010-008-9990-3
The microenvironment plays a critical role in directing the progression of stem cells into differentiated cells. So we investigated the role that cardiac microenvironment plays in directing this differentiation process. Adipose tissue-derived stem cells (ADSCs) were cultured with cardiomyocytes directly (“co-culture directly”) or by cell culture insert (“co-culture indirectly”). For co-culture indirectly, differentiated ADSCs were collected and identified. For co-culture directly, ADSCs were labeled with carboxyfluorescein succinimidyl ester (CFSE), Fluorescence-activated cell sorting was used to extract and examine the differentiated ADSCs. The ultrastructure and the expression of cardiac specific proteins and genes were analyzed by SEM, TEM, western blotting, and RT-PCR, respectively. Differentiated ADSCs experienced the co-culture presented cardiac ultrastructure and expressed cardiac specific genes and proteins, and the fractions of ADSCs expressing these markers by co-culture directly were higher than those of co-culture indirectly. These data indicate that in addition to soluble signaling molecules, direct cell-to-cell contact is obligatory in relaying the external cues of the microenvironment controlling the differentiation of ADSCs to cardiomyocytes.
Co-reporter:Yanxia Zhu;Kedong Song
Journal of Materials Science: Materials in Medicine 2009 Volume 20( Issue 3) pp:799-808
Publication Date(Web):2009 March
DOI:10.1007/s10856-008-3636-6
The architecture and biomaterial are vital for three-dimensional culture of cells in scaffolds, so collagen–chitosan scaffolds suitable for the proliferation of adipose tissue-derived stem cells (ADSCs) were fabricated in this study. Chitosan was fully mixed with collagen with different volume ratio and cross-linked. The microstructure, pore size, bibulous ability, water content, interval porosity, enzyme degradation and affinity were examined before and after cross-linking. During ADSCs cultured in scaffold, the viability and metabolic rates were measured. After 14 days, the surface markers, specific transcription factors and multi-differentiation potential were assayed to identify the stemness of expanded cells. According to the pore size, bibulous ability, interval porosity, degradation rate and affinity of the scaffold, we chose cross-linked scaffolds of 7:3 material ratio as a better scaffold for ADSCs proliferation, and ADSCs could be expanded by more than 20 times. All expanded cells still maintained stem cell characteristics and pluripotency. So our developed collagen–chitosan scaffolds can promote ADSCs adhesion, expansion, and maintain pluripotency.
Co-reporter:Kedong Song;Zhanfeng Cui;Xiangqin Li;Xuehu Ma
Journal of Biomedical Materials Research Part A 2008 Volume 86A( Issue 2) pp:323-332
Publication Date(Web):
DOI:10.1002/jbm.a.31624
Abstract
Bone tissue engineering has emerged as a promising strategy in the effort to regenerate and repair diseased or damaged bone. The bioreactor, within which engineered bone tissue is cultured, plays a key role in the development of engineered bone graphs. In this work, the potentials of the rotating wall vessel bioreactor (RWVB) and the human bio-derived bone scaffolds (BDBS) for 3D bone culture are evaluated. The osteoblasts isolated from the cranium of neonatal Sprague-Dawley (SD) rat of 3 days old were expanded firstly with microcarrier suspension culture in a RWVB. After the assessment of the biological functions of the expanded cells by histomorphometry, the cells were seeded at 2 × 106 and 1 × 106 cells/mL, respectively, onto the 3D human BDBS and cultured for 3 weeks in the RWVB. The cells metabolism and nutrient concentration were monitored in the whole culture processes. The structure of the harvested bone tissues was observed with optical microscope and scanning electron microscope (SEM). The biological properties of the engineered bone were detected by alkaline phosphatase (ALP) expression and alizarin red staining to visualize the newly formed bone. Acridine orange/ethidium bromide (AO/EB) double fluorescence staining was used to analyze the cell activity. For a comparative study, cell seeded constructs were also cultured in static conditions. The results indicate that the bone grafts cultured in RWVB with two different seeded cell densities grew well, and the cell number expanded in RWVB was five times as that in T-flask and spinner flask. There were significantly more collagen fibers mineralized nodules and new osteoid tissue formed than those in T-flask and spinner flask. It also demonstrated that with the stress stimulation inside the fluid in the RWVB, the ALP expression could be increased; the formation of mineralized nodules can be accelerated. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Co-reporter:Kedong Song;Hu Zhao
Frontiers of Chemical Science and Engineering 2008 Volume 2( Issue 1) pp:34-39
Publication Date(Web):2008 March
DOI:10.1007/s11705-008-0022-3
Large-scale expansion of the osteoblasts of a Sprague-Dawley (SD) rat was studied in a rotating wall hollow-fiber membrane bioreactor (RWHMB) by using hollow-fiber membrane as the carrier. For the sake of contrast, cells were also expanded in a T-flask using a hollow-fiber membrane as carrier and in a rotating wall vessel bioreactor (RWVB) using a microcarrier. During the culture period, the cells were sampled every 12 h, and after 5 days, the cells were harvested and evaluated with scanning electron microscopy (SEM), hematoxylin-eosin (HE) staining and alkaline phosphatase (ALP) staining. Moreover, von-Kossa staining and Alizarin Red S staining were carried out for mineralized nodules formation. The results show that in RWHMB, the cells present better morphology and vitality and secrete much more extracellular matrix. It is concluded that the RWHMB combines the advantages of the rotating wall vessel and hollow-fiber membrane bioreactors. The hydrodynamic stimulation within it accelerates the metabolism of the osteoblast and mass transfer, which is propitious to cell differentiation and proliferation.
Co-reporter:Xiubo Fan;Xiangqin Li;Yang Liu
Annals of Biomedical Engineering 2007 Volume 35( Issue 8) pp:1404-1413
Publication Date(Web):2007 August
DOI:10.1007/s10439-007-9305-y
The shortage of hematopoietic stem cells (HSCs) greatly limits their widespread clinical applications. Few studies however, investigated the relationship between the cellular expansion and the influencing factors although wide variety results of the ex-vivo expansion of HSCs existed in literature. Here, a back-propagation (BP) neural network model was employed to evaluate the ex-vivo expansions of nuclear cells (NCs), CD34+ cells, and colony-forming units (CFU-Cs), where the output was the cellular expansion folds and the inputs include inoculated density, cytokines, resources, serum, stroma, culture time, and bioreactor types. Around 124, 86, and 90 samples were used to train the neural network for the expansion evaluations of NCs, CD34+ cells, and CFU-Cs, respectively, while 17, 14, and 10 samples were applied to predict respectively. The results show that for the training of network, the interval accuracy of the expansion folds for the different cells is 85.5, 86.1, and 86.7%, respectively, while the truth-value accuracy is still up to 59.7, 50.0, and 62.2%, respectively within a relative error (RE) of ±20%. For the prediction of network, the interval accuracy can be up to 82.4, 71.4, and 70%, respectively, while the truth-value accuracy is only 29.4, 14.3, and 50.0%, respectively (RE = ±20%). Moreover, six verification experiments were carried out based on our interval predicted values and the results proved that the five group predicted conditions lead to the correct expansion of the HSCs with the accuracy more than 80%. Considering the complexity of HSC expansion and complicated wide range of the experimental data, such relatively high interval accuracy for training and prediction as well as verification are satisfied. Therefore this nonlinear modeling makes it possible to describe quantitatively the effects of the culture conditions on the HSC expansion and to predict the optimal culture conditions for higher ex-vivo expansion of HSCs.
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