Extracellular matrix supports healing of transected rabbit Achilles tendon

Hyaluronic acid/PEO electrospun tube reduces tendon adhesion to levels comparable to native tendons - An in vitro and in vivo study

A major problem after tendon injury is adhesion formation to the surrounding tissue leading to a limited range of motion. A viable strategy to reduce adhesion extent is the use of physical barriers that limit the contact between the tendon and the adjacent tissue. The purpose of this study was to fabricate an electrospun bilayered tube of hyaluronic acid/polyethylene oxide (HA/PEO) and biodegradable DegraPol® (DP) to improve the anti-adhesive effect of the implant in a rabbit Achilles tendon full laceration model compared to a pure DP tube. Additionally, the attachment of rabbit tenocytes on pure DP and HA/PEO containing scaffolds was tested and Scanning Electron Microscopy, Fourier-transform Infrared Spectroscopy, Differential Scanning Calorimetry, Water Contact Angle measurements, and testing of mechanical properties were used to characterize the scaffolds. In vivo assessment after three weeks showed that the implant containing a second HA/PEO layer significantly reduced adhesion extent reaching levels comparable to native tendons, compared with a pure DP implant that reduced adhesion formation only by 20 %. Tenocytes were able to attach to and migrate into every scaffold, but cell number was reduced over two weeks. Implants containing HA/PEO showed better mechanical properties than pure DP tubes and with the ability to entirely reduce adhesion extent makes this implant a promising candidate for clinical application in tendon repair.

Natural Biomaterials from Biodiversity for Healthcare Applications

Natural biomaterials originating during the growth cycles of all living organisms have been used for many applications. They span from bioinert to bioactive materials including bioinspired ones. As they exhibit an increasing degree of sophistication, natural biomaterials have proven suitable to address the needs of the healthcare sector. Here the different natural healthcare biomaterials, their biodiversity sources, properties, and promising healthcare applications are reviewed. The variability of their properties as a result of considered species and their habitat is also discussed. Finally, some limitations of natural biomaterials are discussed and possible future developments are provided as more natural biomaterials are yet to be discovered and studied.

Autologous bone marrow-derived mesenchymal stem cells provide complete regeneration in a rabbit model of the Achilles tendon bundle rupture

PURPOSE

To ascertain the role of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs) in the tendon regeneration.

METHODS

The study was conducted on 58 Achilles tendons from 29 laboratory Chinchilla adult rabbits. The central bundles of 48 tendons were partially removed and substituted with a tissue-engineered construct consisting of a collagen sponge either loaded with BM-MSCs (n = 24) or cell free (n = 24), placed inside a Vicryl mesh tube. The ends of the resected tendon were inserted in the construct to reach a direct contact with the sponge and sutured to the tube. The animals were sacrificed three and six months post-surgery. Ten intact tendons from five rabbits were used as an untreated control. The tissue samples (n = 30) were stained with haematoxylin and eosin, Picrosirius red, primary antibodies to collagen types I and III and studied by bright-field, phase-contrast, polarized light, and scanning electron microscopies followed by semi-quantitative morphometry.

RESULTS

Six months results of cell-loaded scaffolds demonstrated parallel collagen fibres, spindle-shaped tenocytes, and neoangiogenesis. In the control cell-free group, the injured areas were filled with a nonspecific fibrotic tissue with minor foci of incomplete regeneration. The biomechanical tests of 28 tendons taken from 14 rabbits showed that the stiffness of the cell-based reconstructed tendons increased to 98% of the value for the intact samples.

CONCLUSION

The obtained results support the hypothesis that the application of BM-MSCs in a tissue-engineered tendon construct leads to the restitution of the tendon tissue.

Evaluation of a new collagen-based medical device (ElastiCo®) for the treatment of acute Achilles tendon injury and prevention of peritendinous adhesions: An in vitro biocompatibility and in vivo investigation

Tendon healing still represents a challenge for clinicians because it is slow and incomplete. The most injured is the Achilles tendon, and surgery is the therapeutic strategy often adopted because it provides a quicker functional recovery. Peritendinous adhesions are the main complication of surgery with hyperplasia and chemotaxis of fibroblasts. A biomaterial that blocks fibroblast migration, without interfering with the passage of cytokines and growth factors, might be useful. The present study evaluated the biocompatibility of a new Type I collagen-based scaffold (ElastiCo®) and its ability to promote Achilles tendon healing, inhibiting adhesion formation. After verifying in vitro biocompatibility, physical, and mechanical properties of the scaffold, an in vivo study was performed in 28 rats, operated to induce an acute lesion in both Achilles tendons. One tendon was treated with the suture only and the contralateral one with suture wrapped with ElastiCo® film. After 8 and 16 weeks, it was observed that ElastiCo® reduced internal and external peritendinous adhesions and Collagen III content and increased Collagen I. Elastic modulus increased with both treatments over time. Current results highlighted the clinical translationality of ElastiCo® that could improve the quality of life in patients affected by Achilles tendon lesions surgically treated.