Abstract
Purpose :
Ideal biomaterials for functional replacement of vitreous body post vitrectomy surgery remains elusive. Here, we reported a polymer-based biomaterial which is able to act as a resorbable scaffold implant for restoration of a vitreous-like body in-vivo
Methods :
Thermogelling poly(PEG/PPG/PCL urethane) (EPC) co-polymer was synthesized. 23G core vitrectomy was performed on 9 male New Zealand White rabbits. Their vitreous cavity was filled with 7 wt% EPC thermogel. At 1, 2 and 3-month post-surgery, rabbits were sacrificed and vitreous was directly harvested via a 19-guage needle. All animal work performed has been approved by Singhealth IACUC committee. Nuclear magnetic resonance (NMR) and mass-spectrometry (MS) analysis was carried out to determine the polymer degradation and proteomic profiles
Results :
NMR results showed that the EPC polymer was present at 1 month, but undetectable at 3 months in the vitreous cavity. Interestingly, at 3-month post-surgery, upon dissection of the enucleated globes, we noticed the reformation of a vitreous-like body, with a consistency reminiscent of native vitreous. Mass spectrometry based analysis confirmed that the protein composition of this vitreous-like body was highly similar to that of native vitreous, with a 91.13% overlap in total proteins identified. In addition, this vitreous-like body contains major constituents of native vitreous, such as Collagen type II alpha 1, opticin, albumin, fibronectin, retinol binding protein 3, alpha-1-B glycoprotein, transferrin and transthyretin. These proteins were represented with similar abundances in the reformed EPC-7% vitreous-like body, compared to native vitreous. Furthermore, MS analysis did not reveal significant upregulation of proteins associated with an inflammatory response in reformed EPC-7% vitreous-like body.
Conclusions :
We have demonstrated that our EPC-7% gel is biodegradable and it is undetectable by 3 months post-surgery. Clinically, this is relevant as it reduces the need for a second removal surgery unlike clinical equivalents such as silicon oil. EPC-7% gel also promotes the formation of a vitreous-like body in-vivo, with 91.13% similarity to native vitreous. This suggests that EPC-7% gel can function as a long-term clinical vitreous substitute, which can provide continual support for the retina and help prevent subsequent re-detachments.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.