To improve bone engineering for clinical applications, we coupled nanofiber-peptide hydrogel to nano-hydroxyapatite/collagen to form a bioactive scaffold (cnHAC) that mimics extracellular matrices. In comparison to nano-hydroxyapatite/collagen, we found that cnHAC promoted cell adhesion and spreading, and DNA content measurements, alkaline phosphatase activity assays, and reverse transcriptase-polymerase chain reaction analyses of osteogenic gene expression showed that cnHAC significantly improved cellular attachment, proliferation, and osteogenic differentiation in vitro (P < 0.05). In vivo models based on rat calvarial implants showed that cnHAC significantly enhanced bone regeneration (P < 0.05). In conclusion, we demonstrated that novel cnHAC scaffolds could potentially facilitate future bone regenerative medicine.

As the main inorganic component of natural bone, hydroxyapatite has good biocompatibility and osteoconductivity. Conventional sintered hydroxyapatite ceramics are too brittle and have low fatigue strength, thereby limiting their clinical applications. Nano-crystal hydroxyapatite (NHA) ceramic could be prepared by a two-step sintering process and overcomes the disadvantages of brittleness and low fatigue strength. The NHA ceramic provides good mechanical properties that meet the load-bearing requirement of human spine. In this study, animal experiments were performed to evaluate osteointegration and repair effect of the NHA ceramic spinal fusion cage. NHA ceramics intervertebral fusion cages were prepared and implanted into L6-L7 and L7-S1 intervertebral spaces of beagle dogs. The spinal fusion efficacy was evaluated by X-ray imaging and histological observations 2 months and 6 months post-operation. The results showed that the cages and the endplates of the vertebral bodies fused very well 6 months post-operation. Disc space heights were enlarged by the implantation and were not lost post-operation. Histological observations indicated obvious osteointegrations between the implants and the host bone. With good biocompatibility, bioactivity and mechanical strength, NHA is a promising bone substitution material and has a broad application prospect in the field of spinal intervertebral fusion cage.

Dense hydroxyapatite (HA) ceramic is a promising material for hard tissue repair due to its unique physical properties and biologic properties. However, the brittleness and low compressive strength of traditional HA ceramics limited their applications, because previous sintering methods produced HA ceramics with crystal sizes greater than nanometer range. In this study, nano-sized HA powder was employed to fabricate dense nanocrystal HA ceramic by high pressure molding, and followed by a three-step sintering process. The phase composition, microstructure, crystal dimension and crystal shape of the sintered ceramic were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mechanical properties of the HA ceramic were tested, and cytocompatibility was evaluated. The phase of the sintered ceramic was pure HA, and the crystal size was about 200 nm. The compressive strength and elastic modulus of the HA ceramic were comparable to human cortical bone, especially the good fatigue strength overcame brittleness of traditional sintered HA ceramics. Cell attachment experiment also demonstrated that the ceramics had a good cytocompatibility.

Objective:To study the effects of peptide hydrogel composite scaffold on the proliferation and early osteogenic differentiation of rat adipose-derived stem cells(ADSCs).Methods:Nano-Hydroxyapatite/Collagen(nHAC) scaffold was coated by 1% peptide hydrogel.nHAC without peptide coating was set as control.They were characterized by field emission scanning electron microscope(FESEM) and confocal laser scanning microscope(CLSM).ADSCs were chosen to seed onto the nHAC coated and uncoated with peptide hydrogel.CCK-8 kit was used to observe cell proliferation.The alkaline phosphate(ALP) activity was detected the early osteogentic differentiation.Results:Peptide coating was formed on the surface of scaffold.ADSCs adhered to and fully extended on the peptide hydrogel composite scaffold under CLSM.The data of proliferation and ALP continually increased in both groups.There was no difference in cell proliferation at 1 d,3 d(P>0.05).At 5 d,7 d,ADSCs on the coated nHAC proliferated more significantly(P<0.05).There was no difference among 3 d,5 d and 7 d in the ALP activity(P>0.05).Conclusions:The peptide hydrogel composite scaffold could improve adhesion and proliferation of ADSCs,and also can improve early osteogentic differentiation of the cell,although not so obvious as the former two.