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In this study, we fabricated multifunctionalized hydrogel scaffolds based on hyaluronic acid (HA)-tyrosine and human-like collagen (HLC) by crosslinking with 1, 4-butanedioldiglycidyl ether (BDDE) for soft tissue fillers. The physicochemical of HA-tyrosine/BDDE (HTB) and various proportions of HA-tyrosine/BDDE/HLC (HTBH) hydrogels were characterized by swelling ratio, mechanical strength, morphology and thermal stability. The results demonstrated various HTBH hydrogels had superior performance in mechanical properties than HTB hydrogels. The biodegradation in vitro results demonstrated the degradation of HTBH hydrogels were slower than HTB hydrogels, and residual masses of HTBH hydrogels varied with different proportions of HA-tyrosine and HLC in the presence of the combination of HAse/collagenase I. The cell counting kit-8 (CCK-8), Hoechst/PI staining and cell adhesion of various HTBH hydrogels showed less cytotoxic and superior fibroblast attachment than those of HTB hydrogels. Moreover, subcutaneous injections of HTBH hydrogels containing high proportions of HLC in mice and rabbits all exhibit better biocompatibility and anti-biodegradation compared to HTB hydrogels after 1, 4, 8, 12 and 16 weeks. Hematoxylin-eosin staining (H&E), immunohistochemical and transmission electron microscope (TEM) analysis results indicated HTBH hydrogels had less intense inflammatory responses with increase proportion of HLC. Taken together, HTBH hydrogels had great potential application as ideal soft tissue fillers with excellent mechanical properties, biological stability and biocompatibility., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Various tissue scaffold materials are increasingly used to repair skin defects by cross-linking because of the ability to fill and implant in any form via operation. However, crosslinker residues cannot be easily removed from scaffold materials prepared by chemical crosslinking methods, limiting their use for skin tissue engineering. Here, microbial transglutaminase (MTGase), a nontoxic crosslinker with high specific activity and reaction rate under mild conditions, was employed crosslinks in human-like collagen (HLC) to yield novel smart MTGase crosslinked with human-like collagen (MTGH) hydrogels, which are sensitive to temperature and/or enzymes. Various ratios of MTGase/HLC were performed, and their physicochemical properties were characterized, including the swelling ratio, the elastic modulus, the morphology and the porosity. The degradation behavior and mechanism of MTGase in concentration-dependent manner involved in formation hydrogels were identifying in vitro. The cell attachment in vitro and biocompatibility in vivo were also investigated. The results demonstrated that the use of different concentrations of MTGase to crosslink HLC produced products with different degradation times and biocompatibilities. The 50U/g MTGase-prepared MTGH hydrogels had a higher density of crosslinks, which made them more resistant to degradation by collagenase I and collagenase II. However, 40U/g MTGase-prepared MTGH hydrogels were more suitable for cell attachment. In addition, compared with the Collagen Implant I® (SUM) used in animal experiments, the 40U/g MTGase-prepared MTGH hydrogels had a lower toxicity and better biocompatibility. Therefore, 40U/g MTGase crosslinked with HLC should be used to prepare MTGH hydrogels for potential application as soft materials for skin tissue engineering., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Novel hydrogels based on carboxyl pullulan (PC) and human-like collagen (HLC) crosslinking with 1,4-butanediol diglycidyl ether (BDDE) are promising soft fillers for tissue engineering due to their highly tunable properties. Recent studies, however, have shown that incorporating hyaluronic acid and BDDE results in hydrogels with a microporous structure, a large pore size and high porosity, which reduce cell adhesion and enhance degradation in vivo. To improve biocompatibility and prevent biodegradation, the use of PC to replace hyaluronic acid in the fabrication of PC/BDDE (PCB) and PC/BDDE/HLC (PCBH) hydrogels was investigated. Preparation of gels with PC is a promising strategy due to the high reactivity, superb selectivity, and mild reaction conditions of PC. In particular, the Schiff base reaction of HLC and PC produces the novel functional group -RCONHR' in PCBH hydrogels. Twenty-four weeks after subcutaneous injection of either PCB or PCBH hydrogel in mice, the surrounding tissue inflammation, enzymatic response and cell attachment were better compared to hyaluronic acid-based hydrogels. However, the biocompatibility, cytocompatibility and non-biodegradability of PCBH were milder than those of the PCB hydrogels both in vivo and in vitro. These results show that the proposed use of PC and HLC for the fabrication of hydrogels is a promising strategy for generating soft filler for tissue engineering., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A novel, three-dimensional, porous, human-like collagen (HLC)/nano-hydroxyapatite (n-HA) scaffold cross-linked by 1,2,7,8-diepoxyoctane (DEO) was successfully fabricated, which showed excellent mechanical and superior biological properties for bone tissue regeneration in this study. The physicochemical characterizations of different n-HA/HLC/DEO (nHD) scaffolds were investigated by determining the morphology, compression stress, elastic modulus, Young's modulus and enzymatic hydrolysis behavior in vitro. The results demonstrated that nHD-2 and nHD-3 scaffolds showed superior mechanical properties and resistance to enzymatic hydrolysis compared to nHD-1 scaffolds. The cell viability, live cell staining and cell adhesion analysis results demonstrated that nHD-2 scaffolds exhibited low cytotoxicity and excellent cytocompatibility compared with nHD-1 and nHD-3 scaffolds. Furthermore, subcutaneous injections of nHD-2 scaffolds in rabbits produced superior anti-biodegradation effects and histocompatibility compared with injections of nHD-1 and nHD-3 scaffolds after 1, 2 and 4 weeks. In addition, the repair of bone defects in rabbits demonstrated that nHD-2 scaffolds presented an improved ability for guided bone regeneration and reconstruction compared to commercially available bone scaffold composite hydroxyapatite/collagen (HC). Collectively, the results show that nHD-2 scaffolds show promise for application in bone tissue engineering due to their excellent mechanical properties, anti-biodegradation, anti-biodegradation, biocompatibility and bone repair effects. [ABSTRACT FROM AUTHOR]

Skin defects caused by various reasons are currently common clinical problems. At present, hydrogels have been proposed as tissue-engineered skin scaffolds to regenerate the tissues of the defect. We used human-like collagen (HLC), which was isolated and purified after high-density fermentation of recombinant E. coli BL21 The gel uses HLC and carboxymethylated chitosan (CCS) as raw materials and combines enzyme-chemical double cross-linking technology to form a three-dimensional porous network structure that mimics the human extracellular matrix, providing attachment points and nutrients for cell growth and proliferation. For comparison, we used a common hydrogel raw material, gelatin, to prepare a hydrogel in the same way. The experimental results show that the HLC-CCS skin scaffold hydrogel has good mechanical properties, high porosity and good histocompatibility. And full-thickness skin defect repair experiments show that this hydrogel has a good ability to promote skin tissue regeneration at the wound. In summary, this HLC-based double-crosslinked hydrogel can be used as a project strategy for skin defect repair. [ABSTRACT FROM AUTHOR]

New locally injectable biomaterials that are suitable for use as soft tissue fillers are needed to address a significant unmet medical need. In this study, we used pullulan and human-like collagen (HLC) based hydrogels with various molecular weights (MWs) in combination therapy against tissue defects. Briefly, pullulan was crosslinked with NaIO 4 to form a pullulan hydrogel and then may coupled with HLC using the reaction between the –NH 2 end-group of HLC and the –CHO group present on the aldehyde pullulan to form the HLC/pullulan hydrogel, wherein the NaIO 4 acted as the crosslinking and oxidizing agent. The good miscibility of pullulan and HLC in the hydrogels was confirmed via Fourier transform infrared spectroscopy, scanning electron microscopy, compression testing, enzyme degradation testing, cell adhesions, live/dead staining and subcutaneous filling assays. Here, pullulan hydrogels with various MWs were fabricated and physicochemically characterized. Limitations of the pullulan hydrogels included inflammation, poor mechanical strength, and degradation. By contrast, the properties of the HLC/pullulan hydrogels strongly enhanced. The efficacy of these hydrogels was evaluated both in vitro and in vivo. Our results indicate that HLC/pullulan hydrogels may have therapeutic value as efficient soft tissue fillers, with reduced inflammation, improved cell adhesion and delayed hydrogel degradation. [ABSTRACT FROM AUTHOR]