Injectable Tissue-Engineered Cartilage Using a Fibrin Glue Polymer

Abstract

The purpose of this study was to demonstrate the feasibility of using a fibrin glue polymer to produce injectable tissue-engineered cartilage and to determine the optimal fibrinogen and chondrocyte concentrations required to produce solid, homogeneous cartilage. The most favorable fibrinogen concentration was determined by measuring the rate of degradation of fibrin glue using varying concentrations of purified porcine fibrinogen. The fibrinogen was mixed with thrombin (50 U/cc in 40 mM calcium chloride) to produce fibrin glue. Swine chondrocytes were then suspended in the fibrinogen before the addition of thrombin. The chondrocyte/polymer constructs were injected into the subcutaneous tissue of nude mice using chondrocyte concentrations of 10, 25, and 40 million chondrocytes/cc of polymer (0.4-cc injections). At 6 and 12 weeks, the neocartilage was harvested and analyzed by histology, mass, glycosaminoglycan content, DNA content, and collagen type II content. Control groups consisted of nude mice injected with fibrin glue alone (without chondrocytes) and a separate group injected with chondrocytes suspended in saline only (40 million cells/cc in saline; 0.4-cc injections). The fibrinogen concentration with the most favorable rate of degradation was 80 mg/cc. Histologic analysis of the neocartilage showed solid, homogeneous cartilage when using 40 million chondrocytes/cc, both at 6 and 12 weeks. The 10 and 25 million chondrocytes/cc samples showed areas of cartilage separated by areas of remnant fibrin glue. The mass of the samples ranged from 0.07 to 0.12 g at 6 weeks and decreased only slightly by week 12. The glycosaminoglycan content ranged from 2.3 to 9.4 percent for all samples; normal cartilage controls had a content of 7.0 percent. DNA content ranged from 0.63 to 1.4 percent for all samples, with normal pig cartilage having a mean DNA content of 0.285 percent. The samples of fibrin glue alone produced no cartilage, and the chondrocytes alone produced neocartilage samples with a significantly smaller mass (0.47 g at 6 weeks and 0.46 g at 12 weeks) when compared with all samples produced from chondrocytes suspended in fibrin glue (p < 0.03). Gel electrophoreses demonstrated the presence of type II collagen in all sample groups. This study demonstrates that fibrin glue is a suitable polymer for the formation of injectable tissue-engineered cartilage in the nude mouse model. Forty million chondrocytes per cc yielded the best quality cartilage at 6 and 12 weeks when analyzed by histology and content of DNA, glycosaminoglycan, and type II collagen.

Cartilage tissue engineering for degenerative joint disease☆

“…Hydrogels are a class of materials that satisfy the requirements for a successful injectable TE system. Examples of injectable hydrogel systems that have been employed in TE include Pluoronics®, a block copolymer of polyethylene glycopolypropylene glycol [187], collagen [166], Matrigel TM [188], an ECM extract derived from a solubilized basement membrane preparation extracted from EHS mouse sarcoma, and fibrin glue [189]. The injectable polymer systems that crosslink via physical interactions are simple to apply as no external initiator or cross linking agent is required for the hydrogel formation.…”

Non‐enzymatic glycation of chondrocyte‐seeded collagen gels for cartilage tissue engineering

“…Although some techniques involve seeding cells under a physical barrier, such as a periosteal flap, 4 others use an injectable scaffold that may form a solid in vivo. For cartilage tissue engineering, these scaffolds include polymers such as alginate, 5 fibrin glue, 6,7 polyethylene oxide, 8 and PLG microspheres. 9 Central to these injectable techniques are the requirements that these materials have a low viscosity for homogeneous delivery of cells, are biocompatible, act as a template for cartilage repair by providing some initial mechanical support, and support chondrocyte growth and biosynthesis.…”

Electrospinning Technology for Nanofibrous Scaffolds in Tissue Engineering

“…In the presence of thrombin, fibrinogen gives rise to fibrin which forms fibrous clots that have found use as a clinical fixative, due to its natural role in wound healing. Fibrin has recently attracted scientific attention for use as a scaffold to deliver cells [112,113] or growth factors [114] for tissue engineering. Due to the high surface area to volume ratio available for clot formation, electrospun nanofibrous fibrinogen mats are highly suitable for wound dressing and hemostatic products.…”