Surface Modification of Polycaprolactone Scaffold With Improved Biocompatibility and Controlled Growth Factor Release for Enhanced Stem Cell Differentiation

Polycaprolactone (PCL) has been widely used as a scaffold material for tissue engineering. Reliable applications of the PCL scaffolds require overcoming their native hydrophobicity and obtaining the sustained release of signaling factors to modulate cell growth and differentiation. Here, we report a surface modification strategy for electrospun PCL nanofibers using an azide-terminated amphiphilic graft polymer. With multiple alkylation and pegylation on the side chains of poly-L-lysine, stable coating of the graft polymer on the PCL nanofibers was achieved in one step. Using the azide-alkyne “click chemistry”, we functionalized the azide-pegylated PCL nanofibers with dibenzocyclooctyne-modified nanocapsules containing growth factor, which rendered the nanofiber scaffold with satisfied cell adhesion and growth property. Moreover, by specific immobilization of pH-responsive nanocapsules containing bone morphogenetic protein 2 (BMP-2), controlled release of active BMP-2 from the PCL nanofibers was achieved within 21 days. When bone mesenchyme stem cells were cultured on this nanofiber scaffold, enhanced ossification was observed in correlation with the time-dependent release of BMP-2. The established surface modification can be extended as a generic approach to hydrophobic nanomaterials for longtime sustainable release of multiplex signaling proteins for tissue engineering.

Novel scaffold based graphene oxide doped electrospun iota carrageenan/polyvinyl alcohol for wound healing and pathogen reduction: in-vitro and in-vivo study

Wound healing is a complicated multicellular process that involves several kinds of cells including macrophages, fibroblasts, endothelial cells, keratinocytes and platelets that are leading to their differentiation towards an anti-inflammatory response for producing several chemokines, cytokine and growth factors. In this study, electrospun nanofiber scaffold named (MNS) is composed of polyvinyl alcohol (PVA)/iota carrageenan (IC) and doped with partially reduced graphene oxide (prGO) that is successfully synthesized for wound healing and skin repair. The fabricated MNS was tested in case of infection and un-infection with E. coli and Staphylococcus and in both of the presence and in the absence of yeast as a natural nutritional supplement. Numerous biochemical parameters including total protein, albumin, urea and LDH, and hematological parameters were evaluated. Results revealed that the MNS was proved to be effective on most of the measured parameters and had exhibited efficient antibacterial inhibition activity. Whereas it can be used as an effective antimicrobial agent in wound healing, however, histopathological findings confirmed that the MNS caused re-epithelialization and the presence of yeast induced hair follicles growth and subsequently it may be used to hide formed head wound scar.

Development of a Multi-Layer Skin Substitute Using Human Hair Keratinic Extract-Based Hybrid 3D Printing

Large-sized or deep skin wounds require skin substitutes for proper healing without scar formation. Therefore, multi-layered skin substitutes that mimic the genuine skin anatomy of multiple layers have attracted attention as suitable skin substitutes. In this study, a novel skin substitute was developed by combining the multi-layer skin tissue reconstruction method with the combination of a human-derived keratinic extract-loaded nano- and micro-fiber using electrospinning and a support structure using 3D printing. A polycaprolactone PCL/keratin electrospun scaffold showed better cell adhesion and proliferation than the keratin-free PCL scaffold, and keratinocytes and fibroblasts showed better survival, adhesion, and proliferation in the PCL/keratin electrospun nanofiber scaffold and microfiber scaffold, respectively. In a co-culture of keratinocytes and fibroblasts using a multi-layered scaffold, the two cells formed the epidermis and dermal layer on the PCL/keratin scaffold without territorial invasion. In the animal study, the PCL/keratin scaffold caused a faster regeneration of new skin without scar formation compared to the PCL scaffold. Our study showed that PCL/keratin scaffolds co-cultured with keratinocytes and fibroblasts promoted the regeneration of the epidermal and dermal layers in deep skin defects. Such finding suggests a new possibility for artificial skin production using multiple cells.

Preparation of Bio-Inert Carbon Nanofiber Scaffold and Its Effect of Postoperative Injury Nursing and Repair of Bone Tissue

In this research, the characteristics of the bioactive glass (AG) and bio-inert carbon nanofibers (Cnano) in the bone formation was explored. The AG was prepared by sol–gel and combined with polyacrylonitrile (PAN) by electrospinning. Then, Cnano loaded with AG nanoparticles was prepared by carbonization. During the preparation process, the material supply ratio of the sol–gel precursor was changed to obtain 3 nanofiber scaffold materials (Canno/AG_01, Canno/AG_02, and Canno/AG_03). First, the release behavior of silicon ions, calcium ions, and phosphorus ions was investigated during the material preparation process, and Transwell was used for cabin culture, so that bone marrow mesenchymal stem cells (BMSCs) did not directly contact the materials. Besides, the expression levels of osteogenic differentiation genes in different culture sites were detected by reverse transcription-polymerase chain reaction (RT-PCR) method. There was an evaluation of the influences of increased AG content on trauma nursing and chondrocyte apoptosis in vitro. Finally, bone marrow blood mononuclear cells (BMWM) combined with Canno/AG materials were used for clinical research on skull repair. In the experiment, the ion dissolution levels of different prepared materials were different, but they had little effect on the proliferation of BMSCs. Canno/AG_02 with the highest level of silicon ion dissolution had good osteogenic differentiation ability, and RT-PCR proved that contact culture could markedly promote the proliferation and differentiation of BMSCs cells based on the prepared fiber morphology and cell contact effect. Moreover, Canno/AG_02 could be used as the wound dressing for skull fracture to achieve the nursing and rehabilitation effect of wound closure and promoting angiogenesis, and BMWM loaded with Canno/AG_02 could accelerate the tissue healing speed of patients with damaged skull defect.