Bioscaffold implants for volumetric muscle loss: positive results in 13-patient cohort study

Written by Elena Conroy

The study demonstrates that pig tissue-derived bioscaffolds may be an alternative option for patients that do not respond to conventional treatment.

Results of a study conducted by researchers at the University of Pittsburgh School of Medicine and the McGowan Institute for Regenerative Medicine (PA, USA) demonstrated significant improvement in patients who received bioscaffold implants derived from pig tissue to treat volumetric muscle loss — a severe and debilitating clinical problem. Currently, standard of care consists of physical therapy or orthotics or surgical tendon transfers and muscle transfers, which involve donor site morbidity and fall short of restoring function.

In this study, 11 men and two women who had failed to respond to conventional treatment and lost at least 25% of leg or arm muscle volume and function first underwent a customized regimen of physical therapy for 4 to 16 weeks. Lead study surgeon J Peter Rubin UPMC Professor and Chair of Plastic Surgery, Pitt School of Medicine, then surgically implanted a ‘quilt’ of compressed extracellular matrix (ECM) sheets designed to fill in their injury sites. Within 48 h of the operation, the participants resumed physical therapy for up to 24 additional weeks.

“Previously, there was no effective treatment for these patients, but this approach holds significant promise,” stated senior investigator and professor of surgery at Pitt and deputy director of the McGowan Institute. “This approach could be a game changer and not just an incremental advance.”

By 6 months after implantation, patients showed an average improvement of 37.3% in strength and 27.1% in range of motion tasks compared with preoperative performance numbers. CT or MRI imaging also indicated an increase in post-operative soft tissue formation in all 13 patients.

“The three different types of matrix materials used all worked the same, which is significant because it means this is a generic property of these materials and gives the surgeons a choice for using whichever tissue they like,” explained Stephen Badylak. “Prior to the surgery, each patient went through physical therapy focused on getting them to the point where they couldn’t get any better. We then started active rehab 24 hours after surgery, which proved to be critically important for these patients.”

The new data builds upon an earlier Pitt study, which demonstrated that damaged leg muscles grew stronger and showed signs of regeneration in three out of five men whose old injuries were surgically implanted with ECM derived from pig bladder. Those patients also underwent similar pre- and post-operative physical therapy.

The recent results included more patients with varying limb injuries; utilized three different types of pig tissues for ECM bioscaffolds; investigated neurogenic cells as a component of the functional remodeling process; and included CT and MRI imaging to evaluate the remodeled muscle tissue.

“For well-selected patients with this type of loss, we now have a treatment available to help improve their function,” commented Peter Rubin.

Sources: Dziki J, Badylak S, Yabroudi M et al. An acellular biologic scaffold treatment for volumetric muscle loss: results of a 13-patient cohort study. Npj regen. med. doi:10.1038/npjregenmed.2016.8 (2016) (Epub ahead of print);