In situ formed antibacterial hydrogel with collagenase-responsive activity for prevention of MRSA-induced osteomyelitis

Osteomyelitis caused by methicillin-resistant Staphylococcus aureus (MRSA) is a challenging and life-threatening disease due to its long duration and deep site of occurrence. Herein, we design an in situ formed antibacterial hydrogel with collagenase-respontive activity for the prevention of MRSA-induced osteomyelitis. This hydrogel is constructed by chemical bonding between a 4-arm polyethylene glycol maleimide (4-Arm-PEG-Mal), an N-terminal maleimidated antimicrobial peptide (Mal-AMP) and a collagenase-cleavable peptide with two thiol groups (HS-VPM-SH). Collagenase-induced hydrogel cleavage confers on-demand delivery of the antimicrobial peptide, thereby enhancing the combating activity against MRSA in an infected environment. The designed hydrogel, namely AMP/VPM/PEG hydrogel, can be formed rapidly in situ under physiological conditions due to the rapid bonding between the maleimide and thiol groups. In the in vivo rat osteomyelitis model, the AMP/VPM/PEG hydrogel can be administered by simply injecting the 4-Arm-PEG-Mal and peptide solutions with a 26G needle, which is a minimally invasive method. In vivo evaluation further demonstrates that AMP/VPM/PEG hydrogel can successfully prevent MRSA-induced osteomyelitis. This work provides a minimally invasive approach for intramedullary delivery of antimicrobial peptides on-demand and may provide a viable strategy for the osteomyelitis prevention in clinic.