The application of medical devices to repair skin damage is clinically accepted and natural polymer enjoys an important role in this field, such as collagen or hyaluronic acid, etc. However, the biosafety and efficacy of these implants are still challenged. In this study, a skin damage animal model was prepared by UV-photoaging and recombinant humanized type III collagen (rhCol III) was applied as a bioactive material to implant in vivo to study its biological effect, comparing with saline and uncrosslinked hyaluronic acid (HA). Animal skin conditions were non-invasively and dynamically monitored during the 8 weeks experiment. Histological observation, specific gene expression and other molecular biological methods were applied by the end of the animal experiment. The results indicated that rhCol III could alleviate the skin photoaging caused by UV radiation, including reduce the thickening of epidermis and dermis, increase the secretion of Collagen I (Col I) and Collagen III (Col III) and remodel of extracellular matrix (ECM). Although the cell-material interaction and mechanism need more investigation, the effect of rhCol III on damaged skin was discussed from influence on cells, reconstruction of ECM, and stimulus of small biological molecules based on current results. In conclusion, our findings provided rigorous biosafety information of rhCol III and approved its potential in skin repair and regeneration. Although enormous efforts still need to be made to achieve successful translation from bench to clinic, the recombinant humanized collagen showed superiorities from both safety and efficacy aspects.

Titanium (Ti) and its alloys have been frequently used in dental and orthopedic implants, but the undesired oxide layer easily formed on the surface tends to be the cause of implant failure for Ti-based implants. To address this problem, we herein prepared a phosphorylated Ti coating (TiP-Ti) with a micro/nano hierarchically structured topography on commercially pure Ti implants by a hydrothermal method to improve its osteointegration capacity. The surface morphology, chemical composition, and biological activity were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact-angle measurement, and protein adsorption assay. Osteointegration of TiP-Ti implants in rat tibia was investigated by biomechanical testing, micro-CT and histological analyses. We further explored the proposed mechanism which improves osteointegration of TiP-Ti implants by proliferation, adhesion, and differentiation assays of rat bone marrow mesenchymal stem cells (BMSCs). Our results demonstrated that the improved osteointegration mainly benefited from the better spread and adhesion of BMSCs on the micro/nano hierarchically structured TiP-Ti surfaces compared to hydroxyapatite coated Ti (HA-Ti), the positive control, and untreated Ti (untreated-Ti), the negative control. In conclusion, TiP-Ti surface is a promising candidate implant surface design to accelerate the osteointegration of Ti-based implants in biomedical applications.

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Bioinspired by the morphology of osteoclast-resorbed bone surfaces, we prepared a calcium-doped titanium phosphate (Ca-TiP) coating, which consists of a nanofibrous network, on titanium (Ti) substrate via a simple two-step hydrothermal method, trying to mimic natural bone compositionally and microstructurally. The in vitro studies show that the Ca-TiP coating with synergistic features of nanofibrous biomimetic topography and surface chemistry could elicit intensively osteogenic behavior and responses including enhanced cell adhesion, spreading, and proliferation as well as alkaline phosphatase (ALP) activity and up-regulated expression of bone-related genes, which inevitably benefit the formation of new bone and the quality of osseointegration. When the two control groups are compared in vivo, the significantly improved new bone formation in the early stage and the much stronger interfacial bonding with the surrounding bone for Ca-TiP coating suggest that Ca-TiP coating modified Ti implants hold great potential for orthopedic and dental applications.