Decellularized Three-Dimensional Biomimetic Scaffolds as In Vitro Model For Tendon And Meniscus Regeneration.

Traumatic and degenerative injuries to the meniscus and tendon still pose challenges to treatments available in the fields of orthopedics and sports medicine. In search of more effective therapeutic procedures based on biological strategy, regenerative medicine advances like medical science carrying-out preclinical and clinical research necessary for establishing therapeutic efficacy and safety. This research aimed to establish the new concept of three-dimensional decellularized biomimetic scaffolds as in vitro models to investigate the tendon and meniscus regenerative medicine approaches. For this purpose, the menisci of the swine's knee and the tendons of the deep flexor muscles of the bovine's fingers were resected, cleaned, fragmented and frozen (-20°C) for 48 hours. After this, the fragments were thawed and decellularized by immersion in sodium dodecyl sulfate (0.5%) and Triton-X100 (1%) solution for 72 hours. To faithfully simulate a degenerative injury, 0.05 mL of collagenase type-1 (1mg.mL-1/37°C/1hour) was injected into the central region of the meniscal samples. To simulate the traumatic injury, incisions were made on the surface of the samples with a scalpel. The fragments were washed in running water (3 days), immersed in formaldehyde (4%), washed again, stored in ethanol (70%), frozen (-30°C), and submitted to the lyophilization process or embedding in paraffin for histological procedures. For microscopic characterization of tissue and injury sites, histological sections were stained with Hematoxylin and Eosin (HE) or Picrosirius and analyzed under a light microscope with a polarization filter. The results, based on qualitative analysis, demonstrate the preservation of macroscopic and microscopic architecture of the scaffold matrix, the efficacy of the decellularization procedure, and the accuracy in creating the traumatic and degenerative sites of injury. These results allow us to conclude the success of this research in establishing the concept of decellularized three-dimensional scaffolds as a new biomimetic models applicable for in vitro assays evolving regeneration of traumatic and degenerative injuries of tendons and menisci, contributing to the advancement of preclinical research on regenerative medicine approaches.