The role of gelatin and collagen in cell viability and osteogenic potential of an injectable chitosan-based scaffold containing LL37 peptide.

Background and purpose: LL37 peptide is a human antimicrobial peptide with potential application in bone tissue engineering through the stimulation of cell proliferation and osteogenesis. The current study aimed to fabricate chitosan/gelatin/glycerophosphate (CTS/G/GP) and chitosan/collagen/glycerophosphate (CTS/C/GP) thermosensitive hydrogels loaded with LL37 and compared their ability to support cell growth, proliferation, and osteogenesis. Experimental approach: The hydrogel systems were prepared by the physical mixture of chitosan, gelatin, collagen, and GP at the concentrations of 2.5, 1, 1, and 10% w/v, respectively. LL37 was added at a fixed concentration of 1 μg/mL of the hydrogels. The viscosity, friability, release properties, and biological experiments were evaluated based on standard procedures. Findings/Results: The viscosity of CTS/C/GP increased to 7000 cP at 35 °C in 100-120 s, while for CTS/G/GP, the viscosity and gelation time were recorded as 14000 cP and 30 s, respectively. The friability percent for CTS/G/GP after 72 h was reported as 28%, which was significantly lower than that of 38% for CTS/C/GP. LL37 was released during 8 h from both scaffold systems, and it did not demonstrate any significant differences between the hydrogel systems. Cell viability and alkaline phosphatase activity revealed that the incorporation of LL37 in the hydrogels could accelerate cell proliferation compared to empty scaffolds, and it was higher in gelatin-containing scaffolds. Conclusion and implications: LL37 was successfully loaded into both hydrogel systems and demonstrated the ability to accelerate cell proliferation and differentiation compared to the empty scaffold.