Wound Closure Trajectories in Prospective Cohort Study of Lyopreserved Amniotic Membrane

The aims are twofold: to compare cellular viability between cryopreserved and lyopreserved constructs; and evaluate clinical outcomes of the lyopreserved amniotic membrane (LAM).

This was an open-label, prospective cohort study of 40 patients with non-healing foot ulcers. Patients received weekly application of LAM for 12 weeks with standard weekly debridement and offloading. We evaluated the proportion of foot ulcers that achieved closure, the time to closure, closure trajectories, and infection during the course of therapy. We used chi-square tests to compare dichotomous variables and independent t-tests to compare continuous variables with an alpha of 0.10. 

Cellular viability was equivalent between cryo- and lyopreserved amniotic tissue in vitro. Clinically, forty-eight percent of subjects’ wounds closed in an average of 40.0 (SD 20.1) days. Those whose didn’t close were older (63 years vs. 59 years, p=0.011) and had larger ulcers at baseline (7.8cm2 vs. 1.6 cm2, p=0.012). Significantly more patients who achieved closure reached a 50% wound area reduction in 4 weeks compared to non-closed wounds (73.7% vs. 47.6%, p=0.093). There was no difference in the slope of the wound closure trajectories between closed and non-closed wounds (0.124 and 0.159, p = 0.85), indicating that the rate of closure was similar between closed and non-closed wounds. The rate of closure was 0.60 mm/day (SD 0.47) for wounds that closed and 0.50 mm/day (SD 0.58) for wounds that did not close (p=0.89). 

Typically, wound closure in clinical trials is reported as 50% percent wound area reduction at 4 weeks or total closure at 12 weeks. The healing trajectories in this study were similar between the groups of closed and non-closed wounds. Trajectories, and the daily rate of closure, may be more valuable in reporting change in wound size than standard dichotomous endpoints.  

Trademarked Items (if applicable): GrafixPL PRIME, Smith+Nephew, Columbia, MD

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