Absorbable Suture Materials: Preparation and Properties

Radical Ring-Opening Polymerization: Unlocking the Potential of Vinyl Polymers for Drug Delivery, Tissue Engineering, and More

Synthetic vinyl polymers have long been recognized for their potential to be utilized in drug delivery, tissue engineering, and other biomedical applications. The synthetic control that chemists have over their structure and properties is unmatched, allowing vinyl polymer-based materials to be precisely engineered for a range of therapeutic applications. Yet, their lack of biodegradability compromises the biocompatibility of vinyl polymers and has held back their translation into clinically used treatments for disease thus far. In recent years, radical ring-opening polymerization (rROP) has emerged as a promising strategy to render synthetic vinyl polymers biodegradable and bioresorbable. While rROP has long been touted as a strategy for preparing biodegradable vinyl polymers for biomedical applications, the translation of rROP into clinically approved treatments for disease has not yet been realized. This review highlights the opportunities for leveraging rROP to render vinyl polymers biodegradable and unlock their potential for use in biomedical applications.

Tensile strength and knot security of five suture materials exposed to natural summer conditions of a temperate lake

OBJECTIVE

Wild fish and other aquatic ectotherms are often subjected to procedures during field research that require wound closure using sutures. A variety of absorbable sutures are available for such purposes, yet degradation processes are highly dependent on temperature, and the environments in which wild ectotherms are released are almost always colder than the conditions for which absorbable sutures are typically designed (i.e., ~37°C). We therefore studied the degradation of various suture materials under a set of biologically relevant conditions for temperate freshwater fish.

METHODS

Using a force gauge, we tested the tensile strengths and knot securities of loops tied with five different absorbable suture materials (PDS-II, dyed coated Vicryl, undyed coated Vicryl, plain gut, and chromic gut) prior to and during submersion in a temperate lake over an 8-week period.

RESULT

The naturally derived collagen-based suture materials (i.e., plain gut and chromic gut) exhibited major decreases in tensile strength within 2 weeks of submersion but maintained relatively high knot security throughout the study period. The synthetic suture loops had poorer initial knot securities that increased following submersion and showed little to no evidence of degradation after 8 weeks.

CONCLUSION

Variable rates of absorbable suture degradation, or lack thereof, were observed. We discuss the implications of these trends for fish welfare considerations such as suture retention, wound healing, inflammation, and infection under natural conditions.

Tissue Engineered Growth of New Cartilage in the Shape of a Human Ear Using Synthetic Polymers Seeded with Chondrocytes

This report concerns the tissue-engineered growth of new cartilage in the shape of a human ear. Using synthetic biodegradable polyesters, a porous, three dimensional device in the shape of a human ear was fabricated. The polymer matrices were seeded with living chondrocytes isolated from a freshly sacrificed calf shoulder and implanted subcutaneously on the dorsum of athymic rats. This resulted in the formation of new cartilage in the shape of a human ear of approximately the same dimensions as the original implants. Histological analysis revealed the presence of mature cartilage in all specimens.

Biodegradable polymer scaffolds for tissue engineering

Synthetic polymer scaffolds designed for cell transplantation were reproducibly made on a large scale and studied with respect to biocompatibility, structure and biodegradation rate. Polyglycolic acid (PGA) was extruded and oriented to form 13 microns diameter fibers with desired tenacity. Textile processing techniques were used to produce fibrous scaffolds with a porosity of 97% and sufficient structural integrity to maintain their dimensions when seeded with isolated cartilage cells (chondrocytes) and cultured in vitro at 37 degrees C for 8 weeks. Cartilaginous tissue consisting of glycosaminoglycan and collagen was regenerated in the shape of the original PGA scaffold. The resulting cell-polymer constructs were the largest grown in vitro to date (1 cm diameter x 0.35 cm thick). Construct mass was accurately predicted by accounting for accumulation of tissue components and scaffold degradation. The scaffold induced chondrocyte differentiation with respect to morphology and phenotype and represents a model cell culture substrate that may be useful for a variety of tissue engineering applications.