Repairing cartilage that has undergone damage due to trauma, vascular degeneration, or other pathological conditions is a difficult field even now owing to the poor regenerative capacity of cartilage tissue. Physicians and researchers have been looking for pharmaceutical innovations that may potentially regenerate the damaged cartilage.
Cartilage designed by bioengineers via tissue engineering containing a mixture of cells, growth factors and scaffolds has been gaining popularity in the past few years. Their popularity is because of their easy manufacturing process, flexible yet alterable size, multifunctional nature, and variable modes of action. Such cartilage contains numerous peptides that can stimulate the regeneration of cartilage via its scaffold-like structure and functional constituents.
Recent Developments in Cartilage Repair
Since the innovation of autologous chondrocyte implantation (ACI), there have been momentous changes seen in the field of cartilage repair. Currently, the widely used treatment for cartilage repair involves autologous chondrocyte implantation. But ACI has a major drawback as it can have a widely variable outcome due to the potential of the implant to result in abnormal dedifferentiation of chondrocytes which can significantly compromise the therapy’s long-term results.
There has been increasing use of amino acid peptides in the field of bioengineering as peptides simulate the actions of proteins with minimal cost. Peptides play an important role in bone and cartilage growth. Parathyroid hormone is a peptide hormone whose main function is to regulate bone resorption and calcification. Due to its effect on altering bone mineral density, it has been used in certain orthopedic conditions such as osteomalacia and osteoporosis. With knowledge of the important role of peptides in orthopedics, researchers aimed to find the roles of other peptides in cartilage regeneration.
The Role of Peptides in Cartilage Bioengineering
Peptides can exert their effects by imitating, transporting, and accumulating growth factors such as Transforming Growth Factor- β. TGF- β is a growth factor that is important for cell proliferation, synthesis of collagen, and cartilage matrix formation. But due to its volatile structure, it is difficult to procure them in a pure form to use in cartilage repair.
Therefore, using peptides that mimic the structure and function of TGF- β are more stable, cost-effective, durable, and can be easily administered to patients. Cytomodulins are oligopeptides that have highly similar actions as TGF- β such as promoting collagen deposition by enhancing their expression in fibroblasts. They can also accelerate wound healing duration which has been demonstrated by researchers in mouse models.
In addition to this, there are peptides with affinity to mesenchymal stem cells that act via the enrollment of these stem cells. These peptides can also function as scaffolds by simulating a surrounding native to cartilage tissues.
A major difference between TGF- β, and Cytomodulins is the inability of the liquid form of Cytomodulins to efficiently stimulate chondrocyte differentiation. This has been thought to be due to the restricted mobility of the Cytomodulins which slows their metabolic degradation and hinders their activation within the bone marrow. Furthermore, these peptides were found to be quite effective when they were administered in conjugation with microspheres.
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By evaluating the effects of numerous peptides on human umbilical cord mesenchymal stem cells, researchers were able to confirm their hypothesis. Cytomodulins attached to scaffolds were found to be the best approach to employing these peptides to induce chondrocyte differentiation.
As the field of bioengineering is growing exponentially over the past few decades, so is the number of new innovations on cartilage tissue engineering. Within a few years, cartilage tissue engineering with peptides and scaffold may soon replace the conventional autologous cartilage implantation technique.