Jinhuan Tian

Rapid biomimetic mineralization of collagen fibrils and combining with human umbilical cord mesenchymal stem cells for bone defects healing.

Collagen biomineralization is regulated by complicated interactions between the collagen matrix and non-collagenous extracellular proteins. Here, the use of sodium tripolyphosphate to simulate the templating functional motif of the C-terminal fragment of non-collagenous proteins is reported, and a low molecular weight polyacrylic acid served as a sequestration agent to stabilize amorphous calcium phosphate into nanoprecursors. Self-assembled collagen fibrils served as a fixed template for achieving rapid biomimetic mineralization in vitro. Results demonstrated that, during the mineralization process, intrafibrillar and extrafibrillar hydroxyapatite mineral with collagen fibrils formed and did so via bottom-up nanoparticle assembly based on the non-classical crystallization approach in the presence of these dual biomimetic functional analogues. In vitro human umbilical cord mesenchymal stem cell (hUCMSC) culture found that the mineralized scaffolds have a better cytocompatibility in terms of cell viability, adhesion, proliferation, and differentiation into osteoblasts. A rabbit femoral condyle defect model was established to confirm the ability of the n-HA/collagen scaffolds to facilitate bone regeneration and repair. The images of gross anatomy, MRI, CT and histomorphology taken 6 and 12weeks after surgery showed that the biomimetic mineralized collagen scaffolds with hUCMSCs can promote the healing speed of bone defects in vivo, and both of the scaffolds groups performing better than the bone defect control group. As new bone tissue formed, the scaffolds degraded and were gradually absorbed. All these results demonstrated that both of the scaffolds and cells have better histocompatibility.

Alginate/hydroxyapatite hydrogel as biodegradable in situ forming scaffold

The injectable polymer scaffolds are important biomaterials for tissue engineering and drug delivery. Hydrogels derived from natural proteins and polysaccharides are ideal tissue engineering scaffolds since they resemble the extracellular matrices of the tissue comprised of various amino acids and sugar based macromolecules. This work present an injectable system from partially oxidiaed alginate and HA (hydroxyapatite) for tissue engineering and drug delivery applications. In situ release of calcium cations from nano HA particles was adopted through lowering the pH with slow hydrolysis of GDL (D-glucono-δ-lactone) and homogeneous alginate gels were formulated as scaffolds with defined dimensions. The gelation time and the mechanical properties of the system can be controlled by the compositional variables. The SEM observations confirmed a porous 3D hydrogel structure with interconnected pores ranging from 20 to 100 µm and the nano HA particles dispersed in the scaffolds uniformly. The potential applications such as injectable drug delivery vehicle and tissue engineering scaffold are envisaged for this polymer scaffol

Effects of five chitosan oligosaccharides on nuclear factor-kappa B signaling pathway

The effects of five chito-oligomers, from dimer to hexamer (chitobiose, chitotriose, chitotetraose, chitopentaose, chitohexaose) separated from chitosan oligosaccharides, on nuclear factor -kappaB (NF-κB) signaling pathway were investigated by using luciferase assay and laser scanning microscopy. The expression of NF-κB downstream genes (cyclin D1, TNFα and IL-6) were tested by real time PCR. We found that all five chitosan oligosaccharides increased NF-κB-dependent luciferase gene expression and NF-κB downstream genes transcription, and the most significant were chitotetraose and chitohexaose. In addition, laser scanning microscopy experiments showed that chitotetraose and chitohexaose also activated the p65 subunite of NF-κB translocating from cytoplasm to nucleus, which suggested that they were the most potent activators of NF-κB signaling pathway.

A novel biomimetic scaffold with hUCMSCs for lumbar fusion

Discectomy and lumbar fusion are common clinical approaches to treating intervertebral disc (IVD) degeneration with the aid of autologous bone and/or biomaterials. Biomaterials are considered suitable if they are biodegradable and can guide tissue regeneration. These features are necessary for total IVD removal, when it degenerates, as lumbar fusion treatment, avoiding secondary damage caused by the use of autogenous bone. In this work, a novel biomimetic porous chitosan/poly(l-lactic acid) scaffold with human umbilical cord mesenchymal stem cells (hUCMSCs) was applied in lumbar fusion. Hierarchically porous chitosan scaffolds were prepared using molds, porogens and freeze drying, and then poly(l-lactic acid) networks were distributed throughout the interior scaffold to enhance mechanical strength. We conducted cell culture in vitro and animal experiments in vivo. The scaffolds were incubated in hUCMSCs medium and co-cultured for 8 days, and then implanted into half-destroyed IVDs in New Zealand rabbits. The results show that scaffolds with hUCMSCs had greater ability to guide disc regeneration than the blank control and autologous bone, as determined using X-rays, computed tomography, and histologic analyses. Findings confirmed the role of hUCMSCs stimulation in bone-tissue healing and IVD regeneration. This hMUMSCs-based approach, together with the strategy proposed for incorporating osteoblastic cells into scaffolds that promote endogenous or synthetic repair mechanisms, may then be used to develop strategies for the stem-cell-based healing of other acute injuries and chronic diseases.

Fabrication, antibacterial activity and cytocompatibility of quaternary ammonium chitooligosaccharide functionalized polyurethane membrane via polydopamine adhesive layer

In this study, to enhance the antibacterial activity and cytocompatibility of the electrospinning polyurethane (PU) fibrous membrane, quaternary ammonium chitooligosaccharide (G-COS) was immobilized on the fibrous membrane surface via an intermediate layer of polydopamine (PDOPA) to obtain the G-COS functionalized PU (G-C-D-PU), as a control, chitooligosaccharide (COS) functionalized PU fibrous membrane (C-D-PU) was prepared, too. Surface composition, morphology, hydrophilicity and surface energy of the original and modified PU fibrous membranes were characterized, which revealed that the surface roughness and hydrophilicity of the PU fibrous membrane were obviously increased by modified with COS and G-COS, respectively. Antibacterial experiment against E. coli and S. aureus indicated that antibacterial activity of the G-C-D-PU fibrous membrane was markedly superior to that of pure PU and C-D-PU fibrous membranes. In vitro cells culture experiments revealed that the adhesion and proliferation of NIH-3T3 cells on the PU fibrous membrane were improved by successively immobilized with PDOPA and COS as well as G-COS with the concentration of 2 g/L and 6 g/L. Moreover, the G-C-D-PU fibrous membranes with relative high G-COS content were more beneficial to the enhancement of antibacterial activity, but on the contrary, those with relative low G-COS content were more in favor of cell attachment and proliferation.

Dual drug loaded coaxial electrospun PLGA/PVP fiber for guided tissue regeneration under control of infection

Electrospinning promisingly fabricate mats for Guided Tissue Regeneration (GTR). Due to a chronic inflammatory pathology in periodontal, it is highly desirable to develop a novel GTR mats to realize tissue regeneration under control of infection. In the study, coaxial electrospinning was firstly conducted to fabricate dual drug loaded fiber mats with core/shell structure. Naringin-loaded polyvinylpyrrolidone was designed as core fiber to enrich tissue regeneration and metronidazole-loaded poly(lactic-co-glycolic acid) as shell fiber to inhibit bacterial. TEM revealed that the fibers with distinct core/shell structure were in an outer diameter of 1.5-1.7 μm with an inner diameter of <1.0 μm. The loading of dual drug decreased the tensile strength and elongation of the coaxial fiber mats. On in vitro assessment, metronidazole had a short-term release while naringin had a long-term release behavior in all the coaxial mats. The colonization of anaerobic bacteria on the mats effectively were inhibited over 21 days. Furthermore, the dual drug loaded coaxial fiber mats were observed to positively supported the adhesion and proliferation of MC3T3-E1 and was conductive to high alkaline phosphatase express. Thus, a simple and effective coaxial electrospinning approach was demonstrated for the fabrication of anti-infective GTR mats with promoting tissue regeneration.