A Cell-free Biodegradable Synthetic Artificial Ligament for the Reconstruction of Anterior Cruciate Ligament in a Rat Model

Traditional Anterior Cruciate Ligament (ACL) reconstruction is commonly performed using an allograft or autograft and possesses limitations such as donor site morbidity, decreased range of motion, and potential infection. However, a biodegradable synthetic graft could greatly assist in the prevention of such restrictions after ACL reconstruction. In this study, artificial grafts were generated using wet and dry electrospinning processes with a biodegradable elastomer, poly (ester urethane) urea (PEUU), and were evaluated in vitro and in vivo in a rat model. Four groups were established: (1) Wet PEUU artificial ligament, (2) Dry PEUU artificial ligament, (3) Dry polycaprolactone artificial ligament (PCL), and (4) autologous flexor digitorum longus tendon graft. Eight weeks after surgery, the in vivo tensile strength of wet PEUU ligaments had significantly increased compared to the other synthetic ligaments. These results aligned with increased infiltration of host cells and decreased inflammation within the wet PEUU grafts. In contrast, very little cellular infiltration was observed in PCL and dry PEUU grafts. Micro-computed tomography analysis performed at 4 and 8 weeks postoperatively revealed significantly smaller bone tunnels in the tendon autograft and wet PEUU groups. The Wet PEUU grafts served as an adequate functioning material and allowed for the creation of tissues that closely resembled the ACL. Statement of significance In this study, artificial grafts generated using wet electrospinning processes using a biodegradable elastomer, poly (ester urethane) urea (PEUU) were evaluated in vitro and in vivo in a rat model of ACL reconstruction with an emphasis on monitoring cellular infiltration and remodeling along with any changes in the tensile strength of the graft. The synthetic wet PEUU grafts promoted cellular infiltration and neovascularization while also alleviating inflammation and increasing tensile strength. This is the first study showing the utility of Wet-processed PEUU for ACL reconstruction. This artificial ligament could eliminate the need for autograft or allograft tissues, improving clinical and functional outcomes after ACL reconstruction. Wetprocessed PEUU is a practical and effective strategy for ACL reconstruction and may reduce the complications seen with current replacement materials. (c) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study demonstrated that wet-processed PEUU artificial ligaments promoted cellular infiltration, neovascularization, reduced inflammation, and increased tensile strength, making it a practical and effective strategy for ACL reconstruction with the potential to improve clinical and functional outcomes.