More people are surviving cancer than ever before, according to the American Cancer Society. For many, that means an opportunity to think about future plans, including the possibility of having children. Unfortunately, the most common cancer treatments — chemotherapy and radiation — often cause primary ovarian insufficiency and other forms of infertility.
Ovarian tissue cryopreservation, thawing and autografting back into the body is now a common fertility preservation option. However, it may not always be the best approach for all cancer patients. A newer method called in vitro follicle growth or in vitro growth (IVG) shows promise as an alternative.
What Is In Vitro Growth?
IVG is the process of growing follicles in a lab from cryopreserved ovarian tissues and producing mature oocytes for in vitro maturation (IVM) or in vitro fertilization (IVF). It is a viable way to avoid reintroducing cancer cells into patients and perhaps boost the number of oocytes.
Some patients — such as those who have cancers with a high risk of ovarian metastasis or blood-borne leukemias — are not good candidates because autografting ovarian tissue might reintroduce their cancer, according to research published in Fertility and Sterility. In these cases, IVM of oocytes retrieved from growing follicles or complete IVG and IVM of primordial follicles to yield metaphase II (MII) oocytes may be the best option to restore fertility.
Further, IVG may be beneficial for patients beyond those with cancer reintroduction risks. It does not require hormone stimulation, making it suitable for prepubertal children.
How IVG Works
Throughout a patient's reproductive years, most of their follicles are at the primordial stage. Primordial follicles are resting germ cells. During a menstrual cycle, a primordial follicle is recruited first. Then it enters the growth stage, forming a cavity for the oocyte. Finally, the follicle ruptures and releases the oocyte in ovulation.
In vitro growth mimics this in a complex, multistep process:
The culture system should focus on competent oocyte development. This may eliminate the requirement of developing large follicular structures in vitro. While preserving strong oocyte-somatic cell connections, the process must accommodate the changing requirements of the developing oocyte and its somatic cells. As a result, maintaining conditions that enable the maintenance of correctly differentiated somatic cells in touch with the developing oocyte is critical.
Future Research
There have been successes in animal models, according to research published in Acta Obstericia et Gynecologica Scandinavica, but human IVG procedures have yet to produce a live birth, notes a review from Reproductive and Developmental Medicine. Although human IVG approaches have come a long way in recent years, these obstacles must be addressed before in vitro growth may be used to acquire competent oocytes. Producing high-quality oocytes is patient-dependent and will need to be studied extensively across age groups before IVG becomes a strong contender for fertility preservation in cancer patients.
