From conception till birth, the body structure of any species is generated through biological processes. In humans, the development of a mature foetus from a zygote involves multiplication of cells and their controlled and co-ordinated tissue growth, movement, and differentiation. And following further phases of degeneration and regeneration of tissues and organs, man comes to full form.
Regeneration continues throughout human life. It is what is responsible for speedy healing of any injury or ill-developed organs. Some organs, such as the liver, are known to regenerate easily. But this isn’t the case with all organs and the inability to regenerate in response to injuries or diseases can sometimes be fatal.
Regenerative medicine is thus directed towards healing fractured bones, burns, blindness, deafness, damage of muscle, nerve, blood vessel, etc. Age-related degeneration and damage can also be repaired by such therapy. The therapy uses the patient’s own tissue from other body parts to heal the injured site. Metallic and plastic materials are often used to repair tissue damage, but the chances of the body rejecting these materials and creating hurdles in healing are high owing to their bio-incompatibility.
Damaged tissues are generally replaced naturally with the help of primitive progenitor cells or ‘stem cells’ within the body itself. Stem cells can places into two categories, embryonic stem cells, and adult stem cells. The embryonic stem cells (ESC) have an unlimited capacity for self-renewal. Their abilities were explored only when the cells were first available to manipulate in laboratories. The major contributor to the study of these stem cells was the rise of In Vitro Fertilization (IVF) as an Assisted Reproductive Technology.
IVF generates numerous embryos for the treatment of infertility. Two to three embryos fertilised in vitro are transferred into the uterine cavity per cycle. If conception takes place, the leftover embryos are usually donated for research purposes.
Controversies have been aplenty over the use of such embryonic cells for study and experimentation, but their significance in expanding our understanding of the human body cannot be argued—neither can their benefits, considering how they can be cultured and engineered into necessary cell types. For example, the development of insulin producing cells of the pancreas could save the lives of many sufferers of Type 1 diabetes.
Adult stem cells, on the other hand, are localised within a variety of tissues and organs but possess limited ability to divide, differentiate, and renew. Little is known about the degree of their plasticity and there are difficulties in purifying and culturing these cells. These still play a great role, however, in tissue regeneration and repair; they migrate to the site of injury and differentiate into blood cells, cartilage, bone, fat cells and even outer layer of blood vessels to help in healing.
Interestingly, research has found similar properties of differentiation and development in umbilical cord blood cells as those seen in ESCs, except that cord blood cells are much more readily available. These also multiply fast and can be channelled into many areas according to culture conditions—useful in replacing liver cells, producing skin grafts for skin diseases, in helping deal with osteoporosis, neurological conditions, and in repairing heart tissue and blood vessels. So far, extensively concentrated areas of medical research include diabetes, Parkinson’s disease, Alzheimer’s and cancer.
As promising as stem cell research might be, the actual process of culturing these tissues for therapy—and isolating, storing and transplanting them—is not easy. It is a high-tech procedure that employs Reverse Transcription—Polymerase Chain Reaction, immunostaining and imaging, and flow cytometry analysis techniques among others.
Numerous researches are underway around the world, of course, and large scale expansions of these cord blood cells into numerous cell types are already being produced. These cells have a very good international market, but Nepal has yet to jump on the bandwagon. India, for instance, boasts many institutions where regenerative medicine has been well advanced. It is therefore important that we too establish biomedical engineering institutions where tissue engineering can be expanded with foreign collaboration.
It was only in the last decade that the miracles of stem cells became known to man. Already many countries are making use of the newfound knowledge. If all goes well, we might be using stem cells to counter all diseases in the form of easy-to-access tablets, ointments, or injections in the near future, hopefully reducing the use of chemicals. There is much to learn in this still largely unexplored, fascinating field of study and the time to do it is now.
Dr Shrivastava is founder of the Infertility Centre in Bijulibazaar