Surgical advance for robot-assisted orthotopic/heterotopic ovarian tissue transplantation technique by Oktay’s group is indeed praise-worthy.  However, using this advance to discuss what more is needed to make ovarian tissue cryopreservation (OTC) with subsequent orthotopic transplantation as a potential treatment option for women a method of standard care was not compelling.  In addition to citing Oktay’s 2000 article, we also need to discuss their article of 2011 (1) where four spontaneous pregnancies were reported and three live births following heterotopic transplantation of ovarian tissue.  They had discussed a role of stem cells and their niche.   

There are stem cells in the ovary as well as in the testis which survive oncotherapy (2,3) and can regenerate non-functional gonads on transplantation of niche cells (mesenchymal stromal cells).  This has been shown by several groups in mice resulting in live births which was compiled as a systematic review (4) and our group has further shown that although stem cells survive oncotherapy,  their niche gets affected by oncotherapy (5).

It may be best to undertake few clinical studies to study the effect of transplanting autologus mesenchymal stromal cells in non-functional ovary/testis before planning to make OCT followed by orthotopic transplantation a method of standard care.  We have discussed this earlier also (6).

• Oktay K, Türkçüoğlu I, Rodriguez-Wallberg KA. Four spontaneous pregnancies and three live births following subcutaneous transplantation of frozen banked ovarian tissue: what is the explanation? Fertil Steril. 2011;95(2):804.e7-10.
  
• Sriraman K, Bhartiya D, Anand S, Bhutda S. Mouse ovarian very small embryonic-like stem cells resist chemotherapy and retain ability to initiate oocyte-specific differentiation. Reprod Sci. 2015;22(7):884-903.
  
• Anand S, Bhartiya D, Sriraman K, Mallick A. Underlying mechanisms that restore spermatogenesis on transplanting healthy niche cells in busulphan treated mouse testis. Stem Cell Rev. 2016;12(6):682-697.
  
• Fazeli Z, Abedindo A, Omrani MD, Ghaderian SMH. Mesenchymal stem cells (MSCs) therapy for recovery of fertility: a systematic review. Stem Cell Rev. 2017; doi:10.1007/s12015-017-9765-x.
  
• Bhartiya D, Anand S. Effects of oncotherapy on testicular stem cells and niche. Mol Hum Reprod. 2017;23(9):654-655.
• Bhartiya D. Use of very small embryonic-like stem cells to avoid legal, ethical, and safety issues associated with oncofertility. JAMA Oncol 2016; 2 : 689.