Adhesion and collagen production of human tenocytes seeded on degradable poly(urethane urea)

The results of preventing postoperative achilles tendon adhesion using cross-linked and non-cross-linked hyaluronic acid, a study with rat model

BACKGROUND

There are many adhesion barrier materials, cross-linked or non-cross-linked hyaluronic acid (HA), used during surgeries.

PURPOSE

This study investigates the efficacy of cross-linked and non-cross-linked HA in preventing Achilles tendon adhesions. We hypothesized that non-cross-linked HA may be more effective than cross-linked HA in preventing Achilles tendon adhesions following injury and repair.

METHODS

Twenty male Sprague Dawley rats, totaling 40 legs, underwent Achilles tendon transection and repair. Following the surgery, they were treated simultaneously with cross-linked and non-cross-linked HA formulations. The rats were divided into four groups: a positive control group, a group treated with BMC non-cross-linked HA gel, a group treated with DEFEHERE cross-linked HA gel, and a group treated with ANIKA cross-linked HA gel. Four weeks after surgery, macroscopic evaluation of peritendinous adhesion and histological analysis were conducted to assess the effectiveness of the treatments.

RESULTS

Non-cross-linked BMC HA demonstrated superior efficacy in preventing tendon adhesions compared to cross-linked HA and control groups. Histological analysis confirmed reduced adhesion severity in the non-cross-linked HA group (P < 0.05). The findings support the potential of non-cross-linked HA as a treatment to inhibit tendon adhesions. Further research, including clinical trials, is warranted to validate these results in human subjects.

CONCLUSIONS

Non-cross-linked BMC HA had significantly lower tendon adhesions parameters and better healing scores in histological analysis than cross-linked HA and control group did. Non-cross-linked HA holds promise as a potential treatment to inhibit the formation of such adhesions.

Triggerable Degradation of Polyurethanes for Tissue Engineering Applications

Tissue engineered and bioactive scaffolds with different degradation rates are required for the regeneration of diverse tissues/organs. To optimize tissue regeneration in different tissues, it is desirable that the degradation rate of scaffolds can be manipulated to comply with various stages of tissue regeneration. Unfortunately, the degradation of most degradable polymers relies solely on passive controlled degradation mechanisms. To overcome this challenge, we report a new family of reduction-sensitive biodegradable elastomeric polyurethanes containing various amounts of disulfide bonds (PU-SS), in which degradation can be initiated and accelerated with the supplement of a biological product: antioxidant-glutathione (GSH). The polyurethanes can be processed into films and electrospun fibrous scaffolds. Synthesized materials exhibited robust mechanical properties and high elasticity. Accelerated degradation of the materials was observed in the presence of GSH, and the rate of such degradation depends on the amount of disulfide present in the polymer backbone. The polymers and their degradation products exhibited no apparent cell toxicity while the electrospun scaffolds supported fibroblast growth in vitro. The in vivo subcutaneous implantation model showed that the polymers prompt minimal inflammatory responses, and as anticipated, the polymer with the higher disulfide bond amount had faster degradation in vivo. This new family of polyurethanes offers tremendous potential for directed scaffold degradation to promote maximal tissue regeneration.

Assessment of essential characteristics of two different scaffolds for tendon in situ regeneration

PURPOSE

Rotator cuff tears are challenging as the rate of re-ruptures remains high. Thus, new therapeutic strategies need to be developed. Tendon in situ regeneration (TSR) attempts to produce cell-scaffold constructs in vitro, which can produce tendinous tissue of high quality after replantation. Therefore, it is essential to find suitable scaffolds that can provide acceptable biofunctionality and biocompatibility. This study compares characteristics of scaffolds for in situ regeneration: a polyglycolic acid/PDS scaffold (PP-sca) (Ethisorb, Ethicon, Germany) and a collagen sponge (col-spo) (TissueTek, Germany) with a basal strengthening membrane.

METHODS

Tendon-derived cells (TDCs) were isolated from the long head of the biceps tendon. Gene expression for collagen type I, collagen type III, decorin, scleraxis and tenomodulin was analysed in the third cell passage. Cell proliferation in cell seeded scaffolds was tested using a WST-1 assay. In addition, the tensile strength of both scaffolds was measured using a universal-testing machine (Zwick/Roell, Ulm, Germany).

RESULTS

The results from this study indicate a genotypic drift during the in vitro cultivation of the TDCs. The PP-sca showed good biofunctional results, including low initial loss of cells after cell seeding. The proliferation rates were approximately equal in each type of scaffold. The col-spo provided superior tensile strength compared with the PP-sca (p < 0.01).

CONCLUSION

Overall, the col-spo seems to be more suitable for TSR. It may become a clinical alternative in the future to achieve more satisfying results, concerning function and pain.

LEVEL OF EVIDENCE

Experimental study/case series, Level IV.