Table 2 Mesenchymal Cells to Restore Spermatogenesis

Hsiao et al., 2015 [46]

Six to eight-week-old Sprague–Dawley rats underwent torsion for 3 h, followed by detorsion on the left testis. 3 × 10⁴ MSCs from human orbital fat tissues (OFSCs) were injected via local injection into the left testis 30 min before detorsion.

Animals were sacrificed 7 days after torsion-detorsion. Local injections of OFSCs prevented torsion-induced infertility. Serum testosterone secretion was increased, while the elevation of FSH triggered by testicular injury was balanced. OFSCs also produced SCF in the damaged testis. Immunofluorescence staining revealed that most transplanted cells surrounded the Leydig cells. Some of transplanted cells differentiated into p450 expressing cells within 7 days.

Mehrabani et al., 2015 [47]

Rat adipose tissue derived mesenchymal stem cells (ATMSCs) were injected in chemoablated testis (two doses of 10 mg/kg of busulfan with 21 days interval) into the efferent duct of right testes. Seminiferous tubules treated with ATMSCs had normal spermatogenesis whereas the untreated seminiferous tubules were empty.

Abd El Dayem et al., 2015 [48]

Studies were done to restore fertility and reproductive functions after testicular failure induced by butributyltin oxide. Rats were injected a single dose of intravenous MSCs (3×10⁶ cells) and followed up after 5 months. Transplantation of MSCs restored body weight, fertility rate, serum testosterone, LH, FSH hormones, testicular enzymes, sperm counts and improved testicular DNA fragmentation. MSCs transplantation showed normal spermatogenesis and complete recovery in germinal layers. A new therapeutic concept for male infertility treatment.

Zahkook et al., 2014 [49]

MSCs were transplanted (1×10⁸ cells via efferent ducts into the seminiferous tubules) in chemoablated rat induced by busulphan treatment. Some restoration of spermatogenesis was noted associated with increase in size of testis. MSCs have potential to trans-differentiate into germ cells and sperm in vivo in testicular microenvironment.

Anand et al., 2014 [25]

Intertubular injection of Sertoli/ bone marrow derived MSCs (1×10⁴ cells) in chemoablated (25 mg/Kg busulphan) mouse testis. Effects were studied after 2 months. The transplanted Sertoli/MSCs aligned as neo-tubules and were a source of growth factors to the VSELs that survived in chemoablated tubules and restored spermatogenesis. GFP tagged MSCs and Sertoli cells invariably always yielded non-green wild type sperm. Thus MSCs did not trans-differentiate, rather provided a healthy niche for VSELs to differentiate into sperm. Chemoablated mice could not mate and hence IVF was carried out using the sperm which resulted in early stage cleavage embryo.

Zhang et al., 2014 [50]

Allogeneic BMSCs were co-cultured in conditioned media derived from cultured testicular Sertoli cells in vitro, and then induced stem cells were transplanted into the seminiferous tubules of a busulfan-induced azoospermatic rat model for 8 weeks. Donor cells survived in recipient seminiferous tubules. Molecular markers of spermatogonial stem cells and spermatogonia (Vasa, Stella, SMAD1, Dazl, GCNF, HSP90α, integrinβ1, and c-kit) were expressed in the recipient testis tissue. No tumor mass, immune response, or inflammatory reaction developed. BMSCs might provide the potential to trans-differentiate into spermatogenic-like-cells, enhancing endogenous fertility recovery.

Cakici et al., 2013 [51]

Busulfan treated rats were injected GFP tagged MSCs via rete testes. After 12 weeks, spermatogenesis was detected in few tubules and GFP+/VASA+ and GFP+/SCP1+ cells in testes indicated the trans-differentiation of MSCs into spermatogenetic cells in the appropriate microenvironment. Rats withcell treatment were mated to show the full recovery of spermatogenesis, and continuous generations were obtained. GFP tagged sperm were noted in offspring also.

Monsefi et al., 2013 [52]

Donor MSCs from bone marrow were transplanted in busulphan (40 mg/Kg) treated rat testis. BrdU labeled MSCs (1.75×10⁵) were transplanted into the seminiferous tubules. The injected BrdU labeled MSCs differentiated to spermatogonia and spermatozoa in the seminiferous tubules of the infertile testis and also to the interstitial cells between tubules.

Sabbaghiet al, 2012 [53]

Rat bone marrow MSCs (5-10×10⁶ cells) were cultured and transplanted via rete testis into torsionedazoospermic testis. Germ cell specific markers (Oct4, Vasa and c-Kit) were monitored for the differentiation of MSCs after transplantation. They did not observe recovery of spermatogenesis.

Aziz et al., 2011 [54]

Bone marrow derived MSCs were transplanted into busulphan treated rats. One group received undifferentiated MSCs while another received transdifferentiated MSCs. Results showed that MSCs have potential for in vitro transdifferentiation into germ cells and in vivo transdifferentiation into spermatids and spermatocytes.

Lassalle et al., 2008 [55]

Total bone marrow cells were transplanted into the seminiferous tubules of germ cells deficient C57B16J mice after one month of busulphan treatment. Found no evidence for transdifferentiation of bone marrow cells into gametes.

Lue et al., 2007 [56]

Bone marrow cells from adult green fluorescent protein (GFP) mice were transplanted into seminiferous tubules and testicular interstitium of busulfan-treated wild-type or c-kit mutant (W/Wv) mice. 10–12 weeks after transplantation, cells were found to survive in recipient testes. Some GFP-positive donor cells appeared like Sertoli cell and expressed FSHR within the seminiferous tubules. GFP-positive cells in the interstitium expressed cytochrome P450 side chain cleavage enzyme (P450scc). Few GFP-positive donor cells had the appearance of spermatogonia or spermatocytes and expressed VASA. However, this was not found in the seminiferous tubules of W/Wv mice. Thus adult bone marrow cells, in a favorable testicular environment, differentiate into somatic and germ cell lineages. The resident neighboring cells in the recipient testis may control site-appropriate stem cell differentiation.