It is well-accepted that most osteogenic differentiation processes do need growth factors assistance to improve efficiency. As a material cue, hydroxyapatite (HAp) can promote osteogenic differentiation of stem cells only in a way. Up to now, rare work related to the relationship between HAp nanostructures and stem cells in osteogenic differentiation process without the assistance of growth factors has been reported. In this study, one-dimensional (1D) HAp nanostructures with tunable length were synthesized by an oleic acid assisted solvothermal method by adjusting the alcohol/water ratio (η). The morphology of 1D HAp nanostructures can be changed from long nanowires into nanorods with the η value change. Different substrates constructed by 1D HAp nanostructures were prepared to investigate the effect of morphology of nanostructured HAp on stem cell fate without any growth factors or differentiation induce media. Human adipose-derived stem cells (hADSCs), a kind of promising stem cell for autologous stem cell tissue engineering, were used as the stem cell model. The experiments prove that HAp morphology can determine the performance of hADSCs cultured on different substrates. Substrate constructed by HAp nanorods (100 nm) is of little benefit to osteogenic differentiations. Substrate constructed on HAp long nanowires (50 μm) causes growth and spread inhibition of hADSCs, which even causes most cells death after 7 days of culture. However, substrate constructed by HAp short nanowires (5 μm) can destine the hADSCs differentiation to osteoblasts efficiently in normal medium (after 3 weeks) without any growth factors. It is surprise that hADSCs have changed to polyhedral morphology and exhibited the tendency to osteogenic differentiation after only 24 h culture. Hydroxyapatite nanostructures mediated stem cell osteogenic differentiation excluding growth factors provides a powerful cue to design biomaterials with special nanostructures, and helps to elucidate the interaction of stem cell and biomaterials nanostructures. The results from this study are promising for application in bone tissue engineering.Keywords: cell viability and spread; HAp nanostructures; osteogenic differentiation; tunable length; without growth factors;

•TiO2 nanorod arrays (TNRs) was fabricated onto Ti substrates using hydrothermal and sintering method.•TNRs had great potential in promoting the osteogenic activity of implants and the bone-implant integration.•TNRs effectively promoted the adhesion, proliferation and osteogenic differentiation of hPDLSCs in vitro.Nanostructure coating on titanium (Ti) implants is well known as a cue for directing osteoblast behavior and function. However, effects of nanostructure coatings on dental stem cells have been rarely explored. In this work, assembled TiO2 nanorod arrays (TNRs) were fabricated on the polished Ti substrates using hydrothermal and sintering methods. The adhesion, morphology, proliferation and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) seeded onto TNRs substrates were evaluated. Ti substrates were used as control. Rougher TNRs showed better hydrophilicity and protein adsorption capacity compared with Ti control. When seeded on TNRs substrates, PDLSCs exhibited more stretched morphology and higher proliferation rate. Cytoskeletal F-actin expression was markedly promoted for PDLSCs cultured on TNRs substrates under osteogenic induction. Alkaline phosphatase (ALP) activity and mineral deposition were also enhanced by TNRs. Moreover, osteogenesis-related markers of ALP, runt related transcription factor 2 (Runx2) and osteopontin (OPN) of PDLSCs cultured on TNRs substrates were significantly up-regulated at both gene and protein levels when compared to Ti substrates. In conclusion, the unique structure of TNRs provided a biocompatible platform for modulating morphology and function of PDLSCs. The promotion of osteogenic differentiation indicated that the surface modification of implants with TNRs may improve the osteogenic activity of implants and the bone-implant integration in future clinical applications.Download high-res image (280KB)Download full-size image

•We applied collagen membranes loaded with SDF-1 to periodontal bone defects.•SDF-1 recruited mesenchymal/hematopoietic stem cells to the wound area.•SDF-1 significantly reduced the CD11b + inflammatory cell response.•SDF-1 increased vascular formation, induced early bone osteoclastogenesis.•SDF-1 promoted the quality and quantity of regenerated bone.Stromal cell-derived factor-1 (SDF-1) recruits adult stem/progenitor cells via its specific receptor, C–X–C motif receptor 4 (CXCR4), to promote heart, kidney and tendon regeneration, but little is known about the effects of SDF-1 on bone regeneration in periodontal diseases. The objective of this study was to investigate whether local administration of SDF-1 in a collagen membrane scaffold enhanced the recruitment of host stem cells and improved periodontal bone defect repair. To this end, bone defects were established on the buccal side of bilateral mandibles in Wistar rats. After application of collagen membranes loaded with SDF-1 or phosphate-buffered saline (PBS) to the defects, the effects of SDF-1 on stem cell recruitment, inflammatory cell responses, angiogenesis, osteoclastogenesis, scaffold degradation, and bone regeneration were evaluated. It showed that SDF-1 recruited host-derived mesenchymal stem cells and hematopoietic stem cells to the wound area and significantly reduced the CD11b + inflammatory cell response. Moreover, SDF-1 increased vascular formation, induced early bone osteoclastogenesis, accelerated scaffold degradation, and promoted the quality and quantity of regenerated bone. Our results suggest that this cell-free approach by local administration of SDF-1 may be an effective strategy for development as a simple and safe technique for periodontal bone regeneration.

Background/purposeGingiva-derived mesenchymal stem cells (GMSCs) are attractive alternative MSC sources because of their relative abundance of sources and ease of accessibility. However, the isolation method for harboring GMSCs remains under discussion. The aim of the study was to isolate and explore in vitro characterization of human GMSCs, and compare stem cell properties with bulk-cultured gingival fibroblasts (GFs).Materials and methodsGMSCs were isolated with limiting dilution method. Tissue-matched bulk-cultured GFs and GMSCs were evaluated in terms of their colony-forming abilities, population doubling capacities, cell surface epitopes, and multilineage differentiation potentials.ResultsGMSCs showed a significantly higher number of colony-forming units-fibroblast (P < 0.001) than bulk-cultured GFs, while the population doubling capacity of GMSCs reduced. Both types of cells were uniformly positive for MSC-associated makers CD44, CD73, CD90, CD105, and CD166, and were negative for hematopoietic markers CD14, CD34, and CD45. The only distinct marker was STRO-1, which was more highly expressed in GMSCs (13.4%) than in bulk-cultured GFs (0.02%). Upon induction, GMSCs displayed the capacity to undergo osteogenic, adipogenic, and chondrogenic differentiation. Real-time polymerase chain reaction showed related gene levels were significantly upregulated (P < 0.001). By contrast, bulk-cultured GFs lacked the capacity to undergo multilineage differentiation, and related gene levels showed no significant difference when compared with control groups.ConclusionThe data validate the effectiveness of limiting dilution method for GMSCs isolation. GMSCs, in contrast to bulk-cultured GFs, harbor stem cell characteristics and can act as alternative cell sources for tissue engineering.

Background/purposeThe effect of aspirin on bone regeneration remains controversial. This study aimed to determine the effect of various concentrations of aspirin on cell viability, osteogenic differentiation, cell cycle, and apoptosis on ST2 cells to find an effective range of aspirin for bone regeneration induction.Materials and methodsCell viability was measured with MTT assay after being stimulated with aspirin for 1 day, 2 days, 3 days, 5 days, and 7 days. Alkaline phosphatase (ALP) activity was measured after cells were treated for 1 day, 3 days, and 7 days. Expression of runt-related transcription factor 2 (Runx-2) was evaluated using Western-blot analysis at 3 days and 7 days. Flow cytometry was used for cell cycle and apoptosis measurement after cells were treated for 48 hours.ResultsLower concentrations of aspirin (1μΜ and 10μM) promoted cell growth and increased ALP levels and Runx-2 expression, while higher concentrations (100μΜ and 1000μΜ) inhibited cell growth (P < 0.05), and lost their effect on ALP activity after 3 days, while even showing an inhibitory effect on the expression of Runx-2. Aspirin at a concentration of 100μM promoted cell mitosis from the S phase to the G2/M phase, and 1000μM arrested the cell cycle in the resting phase G0/G1 (P < 0.05). Parallel apoptosis/necrosis studies showed the percentage of cells in apoptosis decreased dramatically at any dose of aspirin.ConclusionA lower dosage of aspirin could promote ST2 cell growth, osteogenic differentiation, and inhibit their apoptosis which indicates that aspirin can be used as an alternative for bone regeneration.