Updated: Apr 7, 2021
Tissue engineering approaches aim at the development of strategies for the reconstitution of diseased, injured, or congenitally absent tissues and organs. Not only humans can benefit from the advances in this field, but also animals . As in humans, therapeutic protocols in veterinary medicine can use mesenchymal stem cells (MSCs) as a tool to promote the regeneration of damaged tissue/organs. Worldwide, many companies offer stem cell therapy for dogs, cats, and horses. In most countries, these activities are not yet controlled by regulatory agencies, however, there is a high expectation for the establishment of regulations for these procedures for veterinary patients .
Regenerative veterinary medicine frequently uses MSCs for the treatment of acute injuries and chronic disorders, and these procedures are gradually becoming part of the clinical routine. Orthopaedic injuries are one of the most common disorders observed in veterinary clinical practice, therefore, the development of tissue engineering products for orthopaedic applications is of great interest. Among the techniques translated to the clinics, the most advanced therapies are performed in horses. In the equine orthopaedic field, the most frequent clinical use of tissue engineering has been in the treatment of overstrain-induced injuries of tendons. Other types of clinical cases, including bone-fracture repair and cartilage repair, are also being experimentally treated with MSCs [3,4].
Biomaterials of various compositions have been developed for applications in regenerative veterinary medicine. Chitosan, for instance, is a very promising material, which has been considered extremely useful in the field of tissue engineering. This polymer is obtained from the alkaline deacetylation of chitin and is widely distributed in nature. Chitosan and its derivatives exhibit a variety of physicochemical and biological properties, including non-toxicity, biocompatibility and bioactivity resulting in a very attractive substance to act as a biomaterial in diverse applications such as wound healing, bone regeneration, antimicrobial effects, especially when combined with other polymers. Chitosan has been reported to have osteogenic activity and to promote bone mineralization on artificially-made bone defects in animals. The support of chondrogenesis promoted by chitosan can enhance the quality of neocartilage produced and promote tissue integration with the host matrix [5,6].
Figure 1: Schematic representation of chitin and chitosan .
In addition to the use of chitosan, other biomaterials can be used to assist tissue regeneration in animals, as reported by Zhang et al (2019). In this study, 3D bioprinted tissue-engineered bone was used to repair bone tissue defects in the oral and maxillofacial region of dogs using canine bone marrow stromal cells (BMSCs) and nanoporous hydroxyapatite. The oral and maxillofacial region was scanned for 3D printed surgical guide plate and mold by a high-precision printer. As stated by the authors, this tissue engineering approach was able to repair in situ bone defects in experimental Beagle dogs, and also reduced the time of compositing for tissue engineered bone from 8 to 2 days without the effect on the in vivo osteogenesis ability .
Figure 2: Observation of tissue engineered bones in vivo .
1- Badylak, S. F. (2004). Extracellular matrix as a scaffold for tissue engineering in veterinary medicine: Applications to soft tissue healing. Clinical Techniques in Equine Practice, 3(2), 173–181.
2- Marx, C., Silveira, M. D., & Beyer Nardi, N. (2015). Adipose-Derived Stem Cells in Veterinary Medicine: Characterization and Therapeutic Applications. Stem Cells and Development, 24(7), 803–813.
3- Richardson, L. E., Dudhia, J., Clegg, P. D., & Smith, R. (2007). Stem cells in veterinary medicine – attempts at regenerating equine tendon after injury. Trends in Biotechnology, 25(9), 409–416.
4- Brehm, W., Burk, J., Delling, U. et al. Stem cell-based tissue engineering in veterinary orthopaedics. Cell Tissue Res 347, 677–688 (2012).
5- Şenel, S., & McClure, S. J. (2004). Potential applications of chitosan in veterinary medicine. Advanced Drug Delivery Reviews, 56(10), 1467–1480.
7- Zhang, Li & Tang, Junling & Sun, Libo & Zheng, Ting & Pu, Xianzhi & Chen, Yue & Yang, Kai. (2019). Three-dimensional printed tissue engineered bone for canine mandibular defects. Genes & Diseases. 7.