Poly(trimethylene carbonate) based biomaterials for pelvic organ prolapse applications: In vitro study with human vaginal stromal cells

Abstract

Pelvic organ prolapse (POP) is a common condition where pelvic organs such as the bladder, uterus, or rectum descend into or protrude out of the vaginal canal due to weakened pelvic floor muscles and ligaments. Connective tissue weakening has been associated with lower collagen and elastin content as well as altered mechanical properties of the tissues. Risk factors include childbirth, aging, and obesity. POP affects approximately half of women aged over 50 years. Treatment options range from conservative approaches to surgical interventions such as native tissue repair (NTR) or the use of transvaginal meshes (TVM). While conservative treatments suffice for mild cases, approximately 11-19% of women ultimately require surgical intervention. First line surgical treatment of POP is NTR in which pelvic floor defects are repaired by suturing the weakened vaginal fascia or ligaments to reinforce the weakened native tissue. However, the recurrence rate in NTR is high, even up to 30%, Thus, the TVMs made from polypropylene have been used as second line surgical treatment option for POP. Recently, high complication risk associated with TVMs has led to the reclassification of TVM products as high-risk devices by U.S. Food and Drug Administration (FDA). The reclassification and market withdrawal of many TVM products has increased the research of new alternative materials for POP applications. In this study, the benefits of biodegradable poly(trimethylene carbonate) (PTMC) embedded with L-ascorbic acid 2-phosphate (A2P) was studied for POP applications compared to PTMC without A2P. PTMC is biocompatible, flexible polymer owing suitable mechanical properties for POP applications. Further, A2P is a stable ascorbic acid derivative that is shown to increase the proliferation and collagen production of multiple cell types. The aim of the study was to evaluate how A2P affects the cellular response of human vaginal stromal cells (VSCs) cultured on PTMC membranes and to evaluate its potential for POP applications. PTMC membranes with different weight percentages (0 wt-%, 5 wt-% and 10 wt-%) of A2P were seeded with VSCs. The viability of VSCs was studied with LIVE/DEADTM imaging and the proliferation of the cells was measured with CyQUANT® assay. Scanning electron microscopy (SEM) imaging was conducted to assess the morphology of the cells and the material surface. In addition, immunocytochemistry was used to assess the expression of collagen type I, alpha-smooth muscle actin (αSMA) and vinculin in VSCs. The collagen production of VSCs was assessed with SircolTM collagen assay and quantitative real-time reverse transcription polymerase chain reaction (RT-qPCR). Further, the αSMA and elastin expression of VSCs was also assessed with RT-qPCR. Results of this study showed that VSCs remained viable on all the PTMC materials and A2P increased the proliferation of the cells. Further the A2P increased the collagen production of VSCs, augmenting both the total collagen synthesis measured with SircolTM and the expression of collagen type I and type III quantified using RT-qPCR. However, the most optimal proliferation, morphology, attachment, and collagen production was observed with 5 wt-% of A2P, suggesting that higher concentrations may adversely affect the cellular behaviour of VSCs. Further, VSCs on PTMC membrane with 5 wt-% of A2P showed normal fibroblast cell morphology in SEM imaging. Results of this study imply that A2P embedded PTMC is a promising candidate for POP applications.