Effects of Neuronal and Glial Restricted Precursor Cells Transplantation on Erectile Function after Experimentally Induced Spinal Cord Injury

Considerations for the clinical use of stem cells in genitourinary regenerative medicine

The genitourinary tract can be affected by several pathologies which require repair or replacement to recover biological functions. Current therapeutic strategies are challenged by a growing shortage of adequate tissues. Therefore, new options must be considered for the treatment of patients, with the use of stem cells (SCs) being attractive. Two different strategies can be derived from stem cell use: Cell therapy and tissue therapy, mainly through tissue engineering. The recent advances using these approaches are described in this review, with a focus on stromal/mesenchymal cells found in adipose tissue. Indeed, the accessibility, high yield at harvest as well as anti-fibrotic, immunomodulatory and proangiogenic properties make adipose-derived stromal/SCs promising alternatives to the therapies currently offered to patients. Finally, an innovative technique allowing tissue reconstruction without exogenous material, the self-assembly approach, will be presented. Despite advances, more studies are needed to translate such approaches from the bench to clinics in urology. For the 21^st century, cell and tissue therapies based on SCs are certainly the future of genitourinary regenerative medicine.

Glial restricted precursor cells in central nervous system disorders: Current applications and future perspectives

The crosstalk between glial cells and neurons represents an exceptional feature for maintaining the normal function of the central nervous system (CNS). Increasing evidence has revealed the importance of glial progenitor cells in adult neurogenesis, reestablishment of cellular pools, neuroregeneration, and axonal (re)myelination. Several types of glial progenitors have been described, as well as their potentialities for recovering the CNS from certain traumas or pathologies. Among these precursors, glial-restricted precursor cells (GRPs) are considered the earliest glial progenitors and exhibit tripotency for both Type I/II astrocytes and oligodendrocytes. GRPs have been derived from embryos and embryonic stem cells in animal models and have maintained their capacity for self-renewal. Despite the relatively limited knowledge regarding the isolation, characterization, and function of these progenitors, GRPs are promising candidates for transplantation therapy and reestablishment/repair of CNS functions in neurodegenerative and neuropsychiatric disorders, as well as in traumatic injuries. Herein, we review the definition, isolation, characterization and potentialities of GRPs as cell-based therapies in different neurological conditions. We briefly discuss the implications of using GRPs in CNS regenerative medicine and their possible application in a clinical setting. MAIN POINTS: GRPs are progenitors present in the CNS with differentiation potential restricted to the glial lineage. These cells have been employed in the treatment of a myriad of neurodegenerative and traumatic pathologies, accompanied by promising results, herein reviewed.

Stem Cell Therapy for Neurogenic Bladder Dysfunction in Rodent Models: A Systematic Review

PURPOSE

Neurogenic bladder dysfunction (NGB) has an impact on the quality of life, which made it an important research subject in preclinical studies. The present review investigates the effect of stem cell (SC) therapy on bladder functional recovery after the onset of spinal cord injury (SCI), multiple sclerosis (MS), Parkinson disease (PD), and stroke in rodent models.

METHODS

All experiments evaluated the regenerative potential of SC on the management of NGB in rodent models up to June 2019, were included. From 1,189 relevant publications, 20 studies met our inclusion criteria of which 15 were conducted on SCI, 2 on PD, 2 on stroke, and 1 on MS in the rodent models. We conducted a meta-analysis on SCI experiments and for other neurological diseases, detailed urodynamic findings were reported.

RESULTS

The common SC sources used for therapeutical purposes were neural progenitor cells, bone marrow mesenchymal SCs, human amniotic fluid SCs, and human umbilical cord blood SCs. There was a significant improvement of micturition pressure in both contusion and transaction SCI models 4 and 8 weeks post-SC transplantation. Residual urine volume, micturition volume, and bladder capacity were improved 28 days after SC transplantation only in the transaction model of SCI. Nonvoiding contraction recovered only in 56 days post-cell transplantation in the contusion model.

CONCLUSION

Partial bladder recovery has been evident after SC therapy in SCI models. Due to limitations in the number of studies in other neurological diseases, additional studies are necessary to confirm the detailed mechanism for bladder recovery.

Animal models of erectile dysfunction

Erectile dysfunction (ED) is a prevalent male sexual dysfunction with profound adverse effects on the physical and the psychosocial health of men and, subsequently, on their partners. The expanded use of various types of rodent models has produced some advances in the study of ED, and neurophysiological studies using various animal models have provided important insights into human sexual dysfunction. At present, animal models play a key role in exploring and screening novel drugs designed to treat ED.

Early graft of neural precursors in spinal cord compression reduces glial cyst and improves function

OBJECTIVE

Spinal cord injury (SCI) often results in irreversible and permanent neurological deficits below the injury site and is considered a pathological state of functional damage to local neurons and axon fibers. There are several experimental treatments to minimize tissue damage, and recently cell transplantation has emerged as a promising approach in spinal cord repair. The authors undertook this study to evaluate grafting of neural tube precursors as a possible therapeutic strategy in a model of spinal cord compression in the mouse.

METHODS

Compression SCI was induced at the T-13 level in adult male mice. Immediately after injury, neural precursor cells (NPs) were transplanted into the SCI lesion cavity in 18 mice; the remaining 19 mice received saline injections into the lesion cavity and were used as controls. Spinal cords were examined 12, 19, and 26 days postinjury to investigate the survival of the NPs and their effects on the cellular environment, glial scar and glial cyst formation, astrogliosis, and microglial activation.

RESULTS

Grafted NPs survived well and integrated into the host spinal cord tissue. Some NPs had differentiated into cells expressing glial and neuronal markers at all 3 end points. Analysis of glial cyst volume showed a lesion volume reduction of 63.2% in the NP-treated mice compared with volume in the injured but untreated mice. There appeared to be no difference in astroglial and microglial activation between untreated mice and treated ones. Sensory and motor tests demonstrated that transplantation of NPs promoted improvement in injured and treated animals compared with controls.

CONCLUSIONS

These results support the therapeutic potential of NPs, demonstrating that they can survive for a long time, differentiate, integrate into the injured spinal cord, and promote functional recovery after SCI.

Glial restricted precursor cell transplant with cyclic adenosine monophosphate improved some autonomic functions but resulted in a reduced graft size after spinal cord contusion injury in rats

Transplantation of glial restricted precursor (GRP) cells has been shown to reduce glial scarring after spinal cord injury (SCI) and, in combination with neuronal restricted precursor (NRP) cells or enhanced expression of neurotrophins, to improve recovery of function after SCI. We hypothesized that combining GRP transplants with rolipram and cAMP would improve functional recovery, similar to that seen after combining Schwann cell transplants with increasing cAMP. A short term study, (1) uninjured control, (2) SCI+vehicle, and (3) SCI+cAMP, showed that spinal cord [cAMP] was increased 14days after SCI. We used 51 male rats subjected to a thoracic SCI for a 12-week survival study: (1) SCI+vehicle, (2) SCI+GRP, (3) SCI+cAMP, (4) SCI+GRP+cAMP, and (5) uninjured endpoint age-matched control (AM). Rolipram was administered for 2weeks after SCI. At 9days after SCI, GRP transplantation and injection of dibutyryl-cAMP into the spinal cord were performed. GRP cells survived, differentiated, and formed extensive transplants that were well integrated with host tissue. Presence of GRP cells increased the amount of tissue in the lesion; however, cAMP reduced the graft size. White matter sparing at the lesion epicenter was not affected. Serotonergic input to the lumbosacral spinal cord was not affected by treatment, but the amount of serotonin immediately caudal to the lesion was reduced in the cAMP groups. Using telemetric monitoring of corpus spongiosum penis pressure we show that the cAMP groups regained the same number of micturitions per 24hours when compared to the AM group, however, the frequency of peak pressures was increased in these groups compared to the AM group. In contrast, the GRP groups had similar frequency of peak pressures compared to baseline and the AM group. Animals that received GRP cells regained the same number of erectile events per 24hours compared to baseline and the AM group. Since cAMP reduced the GRP transplant graft, and some modest positive effects were seen that could be attributable to both GRP or cAMP, future research is required to determine how cAMP affects survival, proliferation, and/or function of progenitor cells and how this is related to function. cAMP may not always be a desirable addition to a progenitor cell transplantation strategy after SCI.