Skin-Derived Tenocyte-like Cells for the Treatment of Patellar Tendinopathy

Background: Recent research of lateral elbow tendinopathy has led to the use of laboratory-amplified tenocyte-like cells. Hypothesis: Ultrasound-guided injection of autologous skin-derived tendon-like cells are effective compared with other injectable therapies for the treatment of refractory patellar tendinosis. Study Design: Randomized controlled trial; Level of evidence, 1. Methods: From 60 patellar tendons in 46 patients with refractory patellar tendinopathy, a 4-mm skin biopsy was sampled to grow tenocyte-like collagen-producing cells. Patients were allocated into 2 groups: (1) injection with laboratory-prepared, amplified collagen-producing cells derived from dermal fibroblasts and suspended in autologous plasma from centrifuged autologous whole blood or (2) injection with autologous plasma alone. Injections were made into the sites of hypoechogenicity, intrasubstance tears, and fibrillar discontinuity within the patellar tendon. The Victorian Institute of Sport Assessment (VISA) score was used to assess pain, severity, and functional disability. Ultrasound was performed to assess structural and blood flow changes, evaluating 4 criteria: tendon thickness, hypoechogenicity, intrasubstance tears, and neovascularity. Results: In the cell group, mean VISA scores improved from 44 +/- 15 before treatment to 75 +/- 17 at 6 months; in the plasma group, from 50 +/- 18 to 70 +/- 14. Estimated average difference between groups was 8.1, a significantly higher score in the cell group. Patients treated with collagen-producing cells also had significantly faster improvement and a highly significant effect of treatment, with the difference between groups estimated as 2.5 per unit increase in 1/root time. One patient treated with cell therapy had a late rupture and progressed to surgery; histopathology showed normal tendon structure. Conclusion: Ultrasound-guided injection of autologous skin-derived tendon-like cells can be safely used in the short term to treat patellar tendinopathy, with faster response of treatment and significantly greater improvement in pain and function than with plasma alone.