Compassionate topical use of an M101 oxygenating hydrogel in refractory chronic sternal osteitis after coronary artery bypass grafting: a case report

Deep sternal wound infection and chronic sternal osteitis are serious, difficult-to-treat complications of cardiac surgery. M101 (Hemarina SA, Morlaix, France) is a natural extracellular hemoglobin extracted from the marine worm Arenicola marina with a high oxygen-carrying capacity that has been investigated as a topical oxygenating agent in wound healing. A 65-year-old man developed chronic sternal osteitis refractory to repeated surgical debridement, negative-pressure wound therapy (NPWT) and prolonged antimicrobial therapy after coronary artery bypass grafting (CABG). Under compassionate-use authorization from the French National Agency for Medicines and Health Products Safety (ANSM), an M101-based oxygenating hydrogel was applied topically (ten applications, one every two days). Treatment was well tolerated, with no local or systemic adverse events. The wound, initially 2 × 2 cm with bone exposure, showed progressive granulation and epithelialization over the treatment and follow-up period. In this single case, topical M101 hydrogel was temporally associated with progressive granulation and epithelialization of a chronic post-sternotomy wound refractory to standard management. Causality cannot be inferred from a single observation, and further studies are required.