From embryonic stem cells to induced pluripotent stem cells—Ready for clinical therapy?

Embryonic stem cells and induced pluripotent stem cells have increasingly important roles in many different fields of research and medicine. Major areas of impact include improved in vitro disease models, drug screening, and the development of cell‐based clinical therapies. Here, we review the generation and uses of embryonic stem cells compared to induced pluripotent stem cells and discuss their advantages and limitations. We also evaluate the feasibility of clinical therapies and the future prospects for induced pluripotent cell‐based treatments.     

Is xenotransplantation of embryonic stem cells a realistic option?

To test the purported immune privilege of embryonic stem cells (ESC) in the challenging setting of xenotransplantation, 14 immunocompetent baboons were subjected to a coronary artery occlusion-reperfusion sequence and, two weeks later, randomized to receive in-scar injections of culture medium or cardiac-committed mouse ESC engineered to express fluorescent reporter genes driven by cardiac-specific promoters. Two months after transplantation, left ventricular function, as assessed by echocardiography, deteriorated to a similar extent in control and treated baboons. This correlated with failure to identify the grafted cells by X-gal histology and immunofluorescence. Rejection did not seem to be mediated by xenoantibodies, but rather by T lymphocytes and natural killer cells as suggested by positive immunostaining for CD3 and CD56 early after transplantation. There was no increase in circulating levels of regulatory T cells. These data raise a cautionary note about the immune privilege of ESC and suggest that from a mere immunologic standpoint, ESC xenotransplantation is likely to be an unrealistic challenge.     

Secondary surgery in germ cell tumors—when and how extensively should it be performed?

Postchemotherapy RPLND has been used for several decades. Two current issues relating to this surgery are discussed in this article. The selection for surgery and the extent of surgery to be performed continue to evolve.     

Is matrix metalloproteinase required in postnatal testicular tubules for germ cell maturation?

Background/AimCryptorchidism may cause infertility by failed transformation of neonatal gonocytes into adult dark spermatogonia, the putative stem cells for spermatogenesis. Gonocytes migrate centrifugally to the tubular basement membrane to become adult dark spermatogonia. Regulation of this transformation remains unknown. We aimed to investigate neonatal rodent testis matrix metalloproteinase (MMP) production to see whether MMPs loosen extracellular matrix between Sertoli cells to facilitate gonocyte movement.MethodsSprague-Dawley rat testes (n = 4-6 per group) were collected at embryonic day 19 (E19) and postnatal (P) days P0 to 10 for immunohistochemistry. Immunofluorescent confocal images were captured for presence of membrane type 1 MMP (MT1-MMP), matrix metalloproteinase 2 (MMP2), tissue inhibitor of metalloproteinase 2 (TIMP2), mouse VASA homologue, anti-Müllerian hormone, and androgen receptor in tissue sections. Testicular proteins were analyzed by immunoblotting.ResultsMembrane type 1 MMP was strongly present in gonocytes at E19 then decreased, whereas it increased in testicular somatic cells from P0 to P10. Testicular protein levels of MT1-MMP, MMP2, and androgen receptor were constant from E19 to P10. Anti-Müllerian hormone protein sharply decreased after P2, whereas TIMP2 gradually increased from E19 to P10. Gonocytes migrated to basement membrane at P2 to P6.ConclusionMembrane type 1 MMP, MMP2, and TIMP2 were present in testis from E19 to P10 during gonocyte migration and transformation into spermatogenic stem cells. Increased knowledge about germ cell development may aid efforts to improve fertility in cryptorchidism.     

Metal ion levels in patients with a lumbar metal-on-metal total disc replacement: should we be concerned?

The purpose of this study was to evaluate whether concerns about the release of metal ions in metal-on-metal total hip replacements (THR) should be extended to patients with metal-bearing total disc replacements (TDR). Cobalt and chromium levels in whole blood and serum were measured in ten patients with a single-level TDR after a mean follow-up of 34.5 months (13 to 61) using inductively-coupled plasma mass spectrometry. These metal ion levels were compared with pre-operative control levels in 81 patients and with metal ion levels 12 months after metal-on-metal THR (n = 21) and resurfacing hip replacement (n = 36). Flexion-extension radiographs were used to verify movement of the TDR. Cobalt levels in whole blood and serum were significantly lower in the TDR group than in either the THR (p = 0.007) or the resurfacing group (p < 0.001). Both chromium levels were also significantly lower after TDR versus hip resurfacing (p < 0.001), whereas compared with THR this difference was only significant for serum levels (p = 0.008). All metal ion levels in the THR and resurfacing groups were significantly higher than in the control group (p < 0.001). In the TDR group only cobalt in whole blood appeared to be significantly higher (p < 0.001). The median range of movement of the TDR was 15.5° (10° to 22°). These results suggest that there is minimal cause for concern about high metal ion concentrations after TDR, as the levels appear to be only moderately elevated. However, spinal surgeons using a metal-on-metal TDR should still be aware of concerns expressed in the hip replacement literature about toxicity from elevated metal ion levels, and inform their patients appropriately.     

Can haematologic parameters be used to predict testicular viability in testicular torsion?

The purpose of this study was to evaluate the predictive value of haematologic parameters for testicular survival in torsion. Children with testicular torsion (TT) treated in Beijing Children's Hospital from January 2006 to December 2018 were enrolled in this study. Patient data collected in this study included age, symptom duration, preoperative preparation time, cryptorchidism testicular torsion or not, spermatic cord torsion degree, orchiectomy/orchiopexy, testicular volume 3 months after operation by ultrasound in orchiopexy patients and haematologic parameters. The orchiopexy group comprised of 54 patients with a mean age of 135.6 ± 43.73 months, and the orchiectomy group included 58 patients with a mean age of 119.36 ± 60.82 months. The multivariate analysis showed that symptom duration (Odds Ratio = 1.11, p < 0.001), spermatic cord torsion degree (Odds Ratio = 1.006, p = 0.002) and mean platelet volume (MPV; Odds Ratio = 3.697, p = 0.044) were significant predictors of orchiectomy. The cut‐off value for MPV during window time for orchiectomy was 10.55 fl (10^?9 L) and provided a sensitivity of 47.8% and a specificity of 92.6%. This study found that symptom duration, spermatic cord torsion degree and MPV could be indicators of testicular viability in testicular torsion. MPV can provide valuable information before operation which can guide doctors and family members of the patients to select the appropriate treatment.     

DNA fragmentation in morphologically normal spermatozoa: how much should we be concerned in the ICSI era?

Intracytoplasmic sperm injection (ICSI) has revolutionized the treatment of male infertility. However, there are still unanswered questions about the safety of this technique. During ICSI, only morphologically normal and motile spermatozoa are typically used to fertilize an oocyte. We recently reported that in infertile men, spermatozoa with apparently normal morphology may have DNA fragmentation. This finding consequently raised the possibility that spermatozoa with normal-shaped appearance but with DNA fragmentation could be mistakenly selected to fertilize oocytes during ICSI. This concern became more clinically significant following the subsequent finding that the presence of an increased proportion of normal spermatozoa with damaged DNA was negatively associated with embryo quality and pregnancy outcome after ICSI. Herein, we propose and discuss the hypothesis that the examination of DNA integrity in the subpopulation of highly motile (hence viable) and morphologically normal cells (and not in the total sperm population) may provide optimized information in prediction of ICSI success. More importantly, this new way of evaluation may provide reassurance about genomic normalcy and minimal risk of transmission of genetic disease and guide the development of improved methods of selection of spermatozoa with intact DNA to be used in assisted reproduction.