Infertility is a condition in which a sexually active couple fails to conceive, even without using contraceptive techniques after 1 year. The WHO estimates the overall prevalence of primary infertility in India to be between 3.9 and 16.8 percent, although the estimates of infertility may vary widely among Indian states.
Therapeutic approaches like assisted reproductive techniques (ARTs), intra-uterine-insemination (IUI), hormonal and chemotherapy have been applied in infertility clinics. Nonetheless, there are inherent ups and downs associated with the process as well as hopefulness and disappointment for every month that does not result in a pregnancy. Also, these therapies do not achieve biorhythmic control of hormones. The classical dogma regarding female fecundity is that a female is born with fixed number of follicles. However, this has now been challenged by detection of ovarian stem cells (OSC) in the ovarian surface epithelium (ie: in the adult ovary). Proliferation and differentiation of OSCs results in formation of oocytes/egg cell and primordial follicles. Similarly, progenitor cells have also been identified in male testicles. Thus, stem cells can be obtained from these tissue sources as well as from bone marrow and adipose/fat tissue for management of various conditions. The benefits of bone marrow and adipose derived stem cells lie in the ease of harvesting and the availability of more number of cells of mixed population. These stem cells possess the ability to transdifferentiate, which is the process where one cell type committed to a specific lineage can differentiate into a cell type of different lineage. Thus, treatment of infertility with adult stem cells is a promising approach.
Spermatogonial stem cells (SSCs) are the male germ line stem cells, which are responsible for the production of sperms throughout life. Bone marrow derived mesenchymal stem cells have the capacity to transdifferentiate into sperm cells in the microenvironment of seminiferous tubules and testicular sertoli cells. These cells when transplanted can treat male infertility by stimulating spermatogenesis.
Similarly, in cases of female infertility, transdifferentiation into oocytes is possible which can then be used for in vitro maturation (IVM) and fertilization (IVF). Additionally, bone marrow derived mesenchymal stem cells contain a population of Very Small Embryonic Like (VSEL) stem cells. These cells express follicle stimulating hormone-receptor which is the hormone that regulates the development, growth, pubertal maturation, and reproductive processes of the body.
Bone marrow-derived cells may also differentiate into endometrial cells. This may be beneficial in treating conditions like endometriosis as well as increase endometrial thickness which may result in better engraftment of follicle.
Other causes of infertility may also be treated with cellular therapy alone or a combination of cellular and assisted reproductive techniques. In the future it will be possible to genetically modify germ lines to treat and preserve fecundity in infertile patients.