Induced Pluripotent Stem Cells Engineered To Generate Cartilage (Chondrocytes)
When this year’s (2012) Nobel Prize for Medicine was awarded to Shimya Yamanaka (he shared this honor with Sir John B. Gurdon) for induced pluripotent stem cells, there was a section of critics who opined that, this technique was still in its lab stages, and we would have to wait for a very long long time to see the technique being applied to help humans.
A team of Duke Medicine researchers has managed to generate cartilage from pluripotent stem cells which were grown and used in tissue repair of cartilage injury. The study has been published in the Proceedings of the National Academy of Sciences and reports that induced pluripotent stem cells (iPSCs) may be a viable source of patient specific articular cartilage tissue.
Articular cartilage is the tissue found between the joints which make movement possible and painless; in other words, articular cartilage is the shock absorber of joints. Ordinary wear and tear of this tissue or any kind of injury can lead to debilitating and painful condition and progress to severe osteoarthritis. Articular cartilage cannot repair itself and hence osteoarthritis patients often have to opt for joint replacements.
Why are pluripotent stem cells the chosen ones? Adult stem cells have limited abilities and embryonic stem cells are always embroiled in ethical controversies. Pluripotent stem cells are the best bet since these are adult stem cells which have been converted to have properties similar to embryonic stem cells; staying clear off all ethical issues.
What the study aimed to achieve
The research team led by Brian O. Diekman, post doctoral associate in orthopaedic surgery, aimed to use induced pluripotent stem cells generated from adult stem cells derived from bone marrow or fat tissue as an alternative to other tissue engineering techniques.
Researchers were faced with the challenge of generating a population of chondrocytes which differentiated uniformly. The induced chondrocytes had to produce collagen and maintain cartilage and simultaneously all other types of cells that could be formed by the iPSCs should be separated.
- iPSCs derived from adult mouse fibroblasts were treated with a growth medium to induce chondrocyte differentiation.
- The cells were manipulated to produce green fluorescent protein on becoming chondrocytes.
- Green glowing chondrocytes were easily identified and sorted from other cells.
- These cells produced more cartilage components like collagen and exhibited characteristics of cartilage.
- Thus, these engineered chondrocytes could be used to repair cartilage in the human body.
So, what next?
The next phase of research would be use human iPSCs to try out the cartilage growing technique. Farshid Guilak, PhD, Laszlo Ormandy Professor of Orthopaedic Surgery at Duke and senior author of study is quoted in Science Daily,
The advantage of this technique is that we can grow a continuous supply of cartilage in dish. In addition to cell-based therapies, iPSC technology can also provide patient-specific cell and tissue models that could be used to screen for drugs to treat osteoarthritis, which right now does not have a cure or an effective therapy to inhibit cartilage loss.