The biosafety and efficacy of recombinant humanized type VII collagen with a triple-helical structure in acute skin repair

Type VII collagen (Col VII) is a key component of anchoring fibrils that stabilize the dermal-epidermal junction. To elucidate its functional properties and evaluate its biosafety, we designed several constructs C7PX (X = 1-16) of recombinant humanized collagen VII (rhCol VII) for expression in Escherichia coli. Among these, C7P7 exhibited the highest yield (69.03 mg/L), and its circular dichroism spectrum and differential scanning calorimetry analysis displayed characteristic features of a triple-helix structure. Thus, C7P7 was selected as the final rhCol VII candidate for subsequent analysis of physicochemical properties, biosafety, and functional performance. Comprehensive characterization-including peptide coverage analysis, N- and C-terminal amino acid sequencing and molecular weight-confirmed that the rhCol VII possessed an amino acid sequence fully consistent with its theoretical design. Biocompatibility testing, performed in accordance with national standard GB/T 16886, equivalent to ISO 10993, demonstrated excellent biosafety of rhCol VII. In vivo fluorescence imaging of Cy5-labeled rhCol VII showed specific localization to skin tissue following subcutaneous injection, with negligible distribution to major internal organs (heart, liver, spleen, lung, and kidney) at 48 h post-injection. Functionally, rhCol VII markedly enhanced fibroblast proliferation and accelerated wound closure in vivo, confirming its potent biological activity. Collectively, these findings establish rhCol VII as a safe, bioactive macromolecule with promising regenerative potential. Its high production yield, preserved triple-helical structure, and favorable biocompatibility support potential for further development for clinical applications in regenerative medicine.