Summary

Polydeoxyribonucleotide and polynucleotide showed a property of tendon healing and reversal of fatty degeneration of chronic rotator cuff tear in hypercholesterolemic rat model associated with growth factors.

Abstract

Introduction

For chronic rotator cuff tear, the rate of healing failure after surgical repair and fatty degeneration is considerably high. Polydeoxyribonucleotide (PDRN) has been used as a tissue regeneration activator. This study was performed to explore the effects of polydeoxyribonucleotide and polynucleotide (PN) on tendon healing and reversal of fatty degeneration in a chronic rotator cuff tear model using a hypercholesterolemic rat infraspinatus.

Materials And Methods

Fifty six SD male rats were randomly assigned to four groups (14 rats per group: 6 for histological evaluation and 8 for mechanical and blood testing): one normal rat group (saline+repair: NSR), three hypercholesterolemic (HC) diet-induced HC rat groups (saline+repair: HSR, PDRN+repair: HPR, and PN+repair: HPNR). The right shoulder was used for experimental interventions, and the left served as a control. Four weeks after detaching the infraspinatus, the torn tendon was repaired. Saline, PDRN, and PN were applied to the repair sites. And 2 weeks after repair, same materials were injected, again. Histological and mechanical evaluation was performed at 4 weeks after repair and blood analysis on vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), insulin-like growth factor (IGF) was performed using the rats for the mechanical testing at the surgery or repair, 2 and 4 weeks.

Results

At 4 weeks after repair, on biomechanical evaluation, the mean load-to-failures of the right shoulders of HPR and HNPR groups (24.64 ± 10.76 and 20.42 ± 6.21) are higher than that of HSR group (14.33 ± 6.52), but there were no statistically significant differences (p=.086 and p=.528, respectively). The HPR group had more parallel and continuous collagen fibers (p=.028 and p=.028, respectively) and fewer adipose cells in Oil Red O and H&E stains (p=.012 and p=.020, respectively) than the HSR group. And HPNR group had fewer adipose cells than the HSR group, also (p=.012). The HPR and HPNR groups had fewer CD68 stains cells which means a parameter of degeneration than the HSR groups (p=.023 and p=.025, respectively). The mean plasma vascular endothelial growth factor (VEGF) at 2 weeks after repair showed a significant difference between HSR and HPR groups and between HSR and HPNR groups (p=.031 and p=.009). The mean plasma VEGF at 4 weeks after repair showed a significant difference between HSR and HPNR groups (p=.008).

Conclusion

PDRN and PN might have possibility to improve tendon healing and decrease fatty degeneration after cuff repair in hypercholesterolemic state.