Effect of Lactoferrin Peptide (PXL01) on Rabbit Digit Mobility After Flexor Tendon Repair

PurposeRestoration of digital function after flexor tendon injuries remains a clinical challenge. Complications such as adhesion formation and tendon rupture can lead to limited hand function. The aim of this study was to compare the effects of the lactoferrin-derived peptide, PXL01, formulated in sodium hyaluronate (SH), with SH alone on joint mobility as an indirect measure of postsurgical adhesion prevention and healing strength of the tendon and to elucidate the most optimal concentration of PXL01.MethodsUsing a rabbit flexor tendon repair model, in which the deep flexor tendon was fully transected and repaired, PXL01 in SH or SH alone was administered between the repaired tendon and the tendon sheath before closure of the surgical wound. Three concentrations of PXL01 in SH (5, 20, or 40 mg/mL) were compared to determine the lowest effective concentration. The repaired tendons were evaluated 7 weeks after surgery by measuring the proximal interphalangeal joint mobility by full range of flexion assessment and the tendon repair strength.ResultsTreatment with PXL01 formulated in SH resulted in improved mobility of the proximal interphalangeal joint with an average of 10°, corresponding to improvement of approximately 25% to 60% of the flexion of nonoperated toes at the different measuring points compared with SH alone. The difference was statistically significant in 5 out of 6 measuring points (0.5, 1, 2, 3, and 4 N; P < .05). The dose-response study indicated that the lowest effective concentration of PXL01 was 20 mg/mL. There was no difference in healing strength of the tendon between the groups as assessed by load-to-failure breaking strength.ConclusionsPXL01 in SH significantly improved the mobility compared with the carrier SH alone, without any negative effect on healing strength, and PXL01 at 20 mg/mL was the lowest effective concentration.Clinical relevanceThe result provides a valuable basis for a clinical trial to assess efficacy and safety of PXL01 in clinical hand surgery.