Background of the Article
Researchers have successfully induced the differentiation of stem cells into human articular chondrocytes in the lab. In a recent research, April Craft and others generated chondrocyte cells that could form a functional cartilage tissue covering bones at the joints (641). The breakthrough heralds a new era in osteoarthritis therapy, as it is now possible to generate cartilage for joint repair without the need for an invasive joint replacement procedure.
In their research, Craft et al. identified the factors that promote the differentiation of human stem cells into chondrocytes. They activated the TGFβ pathway, a mechanism in the regulation of essential cellular processes, both in a Petri dish and in a model organism. In addition, Craft et al. stimulated a BMP4 signal, a polypeptide involved in the TGFβ pathway, to model the process of cartilage tissue formation in the human body (643). The results show that the stimulation of these two processes in stem cells generates chondrocytes that develop into stable cartilage that can be used to repair joints.
Important Result/Finding of the Study
The study made a groundbreaking discovery of the factors that induce human stem cells to develop into chondrocytes able to differentiate into a stable cartilage tissue (Craft et al. 643). Developing stable chondrocytes from human stem cells had been a challenge and, therefore, the establishment of the necessary conditions for the differentiation process was a breakthrough.
The Potential Impact of the Finding
Human stem cells are inherently pluripotent, i.e., they can form any tissue of the body if subjected to the right conditions. Therefore, the finding that pluripotent stem cells can form cartilage tissue opens a new avenue for the treatment of patients with degenerative joint disorders, such as osteoarthritis. The common medical procedure for treating such patient involves joint replacement surgery, which is often invasive and traumatic. With this discovery, doctors can generate and transplant chondrocytes into a patient to repair damaged joints noninvasively. Therefore, cartilage tissue derived from the chondrocytes can be used to treat degenerative osteoarthritis.
Similar studies have established the potential of pluripotent stem cells to form body tissues by stimulating key cellular processes. Chal et al. studied Duchenne muscular dystrophy (DMD), which is a degenerative disorder of the muscles, by exposing pluripotent cells to specific conditions that promote skeletal muscle development (966). The muscle tissue generated could be grafted into a mouse with DMD. Ogawa et al. also generated ductal structures from cholangiocytes, allowing them to model the development of bile duct disorders in humans (857). The researchers established a protocol for producing cholangiocytes from stem cells.
Researchers have also been able bioengineer organs from pluripotent human stem cells. A team of researchers led by Xi Ren regenerated the pulmonary vascular system by injecting the vasculature with stem cell-derived endothelial cells (134). They developed a culture protocol for introducing and maturing the endothelial cells within the lungs. In another study, Rezania et al. generated “insulin-producing cells from stem cells” using a seven-stage procedure (1126). The generated cells demonstrated remarkable similarities with beta cells that secrete insulin in non-diabetic individuals. Regulated expression of the genes responsible for cell growth has been used to produce cardiovascular progenitor cells that can differentiate into heart tissue (Birket et al. 976). Thus, stem cells, under appropriate conditions, can develop into any part of the body.
Human stem cells can develop into different cell types that differentiate into specialized body tissues. However, the main problem is how to mimic in vivo conditions in the lab to produce progenitor cells. Additionally, ethical issues prevent the use of stem cells derived from human embryos in disease research.
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