IN-VIVO TESTING OF THE BIMODAL SCAFFOLDS IN A RABBIT MODEL

Abstract

Femur and tibia in the human body are connected by the Anterior Cruciate Ligament (ACL), which has limited capacity to self-regenerate due to low level of vascularity. Very few success rates in the clinical procedures to restore the tissue evidence that currently available clinical treatments are not optimal. Therefore, biologically similar, i.e., biomimetic, constructs that resemble healthy native tissue in their function, composition, and structure can be used to provide alternate solutions. The hypothesis of the research is that the graft created from the alignment of Polyethylene terephthalate and Polycaprolactone (PET&PCL) nanofibers with the diameter distribution in a bimodal manner will resemble the healthy rabbit ACL’s collagen fibril diameter distribution (CFDD). Histocompatibility of the ligament and bone growth would be enhanced via the biodegradable portion of the PCL, whereas the non-biodegradable PET portion would retain the integrity to prevent the deterioration of the graft’s mechanical strength. To evaluate this, PET&PCL grafts were synthesized via electrospinning as a first step. Then, the alignment of the nanofibers and their fiber diameter were assessed and put into comparison with native rabbit ACL. As a third step, the mechanical quality of the synthesized grafts was evaluated and compared to the native rabbit ACL. As a final step, PET&PCL grafts were assessed in the rabbit ACL reconstruction model. PET&PCL electrospun graft’s fiber diameter distribution was found to resemble the CFDD of ACL from the healthy rabbits. Also, stiffness and modulus were found to be similar. The novelty of the study is that the nanofiber grafts from PET and PCL resembling CFDD of ACL tissue harvested in healthy rabbits were presented for the first time. This study is significant because the graft designed and fabricated here has the potential to address the needs of millions of patients suffering from ACL tears and ruptures. The design of the fibrous graft in 7 this study diverges from the well-known unimodal structure, and this design is expected to greatly affect ACL regeneration attempts.