Unveiling the superior function of RADA in bone regeneration compared to KSL as two critical cores within self-assembling peptide nanofibers: Insights from in vitro and in vivo studies.

Introduction: Self-assembling peptide nanofibers have emerged as promising biomaterials in the realm of bone tissue engineering due to their biocompatibility, biodegradability, and ability to mimic the native extracellular matrix. This study delved into the comparative efficacy of two distinct self-assembling peptide nanofibers, RADA-BMHP1 and KSL-BMHP1, both incorporating the biological motif of BMHP1, but differing in their core peptide sequences. Methods: Cell viability and osteogenic differentiation in rat mesenchymal stem cells (rMSCs), and bone regeneration in rat were compared. Results: In vitro assays revealed that KSL-BMHP1 promoted enhanced cell viability, and nitric oxide production than RADA-BMHP1, an effect potentially attributable to its lower hydrophobicity and higher net charge at physiological pH. Conversely, RADA-BMHP1 induced superior osteogenic differentiation, evidenced by upregulation of key osteogenic genes, increased alkaline phosphatase activity (ALP), and enhanced matrix mineralization which may be attributed to its higher protein-binding potential and grand hydropathy, facilitating interactions between the peptide nanofibers and proteins involved in osteogenesis. In vivo experiments utilizing a rat bone defect model demonstrated that both peptide nanofibers improved bone regeneration at the genes level and ALP activity, with RADA-BMHP1 exhibiting a more pronounced increase in bone formation compared to KSL-BMHP1. Histological evaluation using H&E, Masson's trichrome and Wright-Giemsa staining confirmed the biocompatibility of both nanofibers. Conclusion: These findings underscore the pivotal role of the core structure of self-assembling peptide nanofibers, beyond their biological motif, in the fate of tissue regeneration. Further research is warranted to optimize the physicochemical properties and functionalization of these nanofibers to enhance their efficacy in bone regeneration applications.