Transplantation of Mesenchymal Stem Cells Derived from Old Rats Improves Healing and Biomechanical Properties of Vaginal Tissue Following Surgical Incision in Aged Rats.

Pelvic floor dysfunction encompasses a group of disorders that negatively affect the quality of women's lives. These include pelvic organ prolapse (POP), urinary incontinence, and sexual dysfunction. The greatest risk factors for prolapse are increased parity and older age, with the largest group requiring surgical intervention being post-menopausal women over 65. Prolapse recurrence rates following surgery were reported to be as high as 30%. This may be attributed to ineffective healing in the elderly. Autologous stem cell transplantation during surgery may improve surgical results. In our previous studies, we showed that the transplantation of bone marrow-derived mesenchymal stem cells (MSCs) from young donor rats improved the healing of full-thickness vaginal surgical incision in the vaginal wall of old rats, demonstrated by both histological and functional analysis. In order to translate these results into the clinical reality of autologous MSC transplantation in elderly women, we sought to study whether stem cells derived from old donor animals would provide the same effect. In this study, we demonstrate that MSC transplantation attenuated the inflammatory response, increased angiogenesis, and exhibited a time-dependent impact on MMP9 localization. Most importantly, transplantation improved the restoration of the biomechanical properties of the vagina, resulting in stronger healed vaginal tissue. These results may pave the way for further translational studies focusing on the potential clinical autologous adjuvant transplantation of MSCs for POP repair for the improvement of surgical outcomes.

The microbiota regulates murine inflammatory responses to toxin-induced CNS demyelination but has minimal impact on remyelination.

The microbiota is now recognized as a key influence on the host immune response in the central nervous system (CNS). As such, there has been some progress toward therapies that modulate the microbiota with the aim of limiting immune-mediated demyelination, as occurs in multiple sclerosis. However, remyelination-the regeneration of myelin sheaths-also depends upon an immune response, and the effects that such interventions might have on remyelination have not yet been explored. Here, we show that the inflammatory response during CNS remyelination in mice is modulated by antibiotic or probiotic treatment, as well as in germ-free mice. We also explore the effect of these changes on oligodendrocyte progenitor cell differentiation, which is inhibited by antibiotics but unaffected by our other interventions. These results reveal that high combined doses of oral antibiotics impair oligodendrocyte progenitor cell responses during remyelination and further our understanding of how mammalian regeneration relates to the microbiota.

Age-associated differences in macrophage response in a vaginal wound healing rat model.

INTRODUCTION AND HYPOTHESIS: Surgical treatment of pelvic organ prolapse often includes the use of patients' vaginal connective tissue. Wound healing appears to play an important part in the success of such procedures. The aim of this study was to describe the effect of age on inflammatory processes, specifically macrophage response, involved in vaginal wound healing. METHODS: Twenty-five young (12 weeks old) and 25 old (12 months old) virgin female Fischer rats underwent a standardized 9-mm posterior midline vaginal incision. Tissue samples were taken for histological analysis on days 1, 3, 7, 14 and 30 post-injury. Parameters evaluated included wound area, macrophage number and expression of inflammatory markers including tumor necrosis factor alpha (TNFa), inducible nitric oxide synthase (iNOS), CCR7/CD197, arginase I and CD163/M130. RESULTS: Microscopic examination of the vaginal wounds over time demonstrated a clear difference between young and old rats in spontaneous healing capacity. The average wound area in young rats 1 day after injury was significantly smaller than in old rats (16.5 ± 1.7 vs. 23.8 ± 1.5 mm2, P < 0.05). At 3 days post-injury, wounds were closed in young rats but still open in old rats (wound area: 13.5 ± 1.5 mm2). Old rats demonstrated a more excessive and sustained macrophage response compared with young rats. They also demonstrated a disordered pattern of macrophage expression over time, with a prolonged expression of TNFa and iNOS in the tissue and a disordered M2 macrophage response. CONCLUSION: Excessive and prolonged macrophage response in older rats may contribute to poor wound healing in the vagina.

Age-associated impairments in tissue strength and immune response in a rat vaginal injury model.

INTRODUCTION AND HYPOTHESIS: Surgical repair of pelvic organ prolapse often includes native tissue repair during which the patient's own vaginal connective tissue is used to achieve pelvic support. This method, based on plication and suspension often yields suboptimal anatomical outcomes, possibly due to inadequate healing of the vaginal connective tissue. We hypothesized that age might have a negative effect on the time course and tissue biomechanics of vaginal wound healing in a rat model. METHODS: Fifty young (12 weeks) and old (12 months) female 344BN Fischer rats were subjected to a posterior midline vaginal incision. The time course of repair was determined by measuring the size of the wound on days 1, 3, 7, and 14 post-injury. These findings correlated with the immune response to injury using a marker of impaired wound healing, the inflammatory cytokine macrophage migration inhibitory factor in the vaginal muscularis. Biomechanical properties of the healed vaginal tissue were tested 30 days post-injury. RESULTS: Wound healing was assessed on days 1, 3, 7, and 14 post-injury. On day 3 post-injury, the wounds in the young animals had all closed whereas the wounds in the old animals remained open. Furthermore, on day 7, the wound gap was still filled with granulation tissue in the old rats, whereas for the young rats, the wound area was almost indistinguishable from the non-injured area. Macrophage migration inhibitory factor was highly expressed in the vaginal epithelium and in the vaginal muscularis after injury. When compared with young animals, macrophage migration inhibitory factor levels of old rats began to rise more than 2 days later and the increased tissue expression persisted for 7 days longer. The breakpoint force of the healed vagina of old rats was almost 4-fold weaker than in young rats. At 30 days post-injury, the healed vagina in old rats regained less of the original (healthy) force at breakpoint than the young rats. CONCLUSIONS: In this rat model, age impaired vaginal wound healing, which was reflected in the altered inflammatory response to injury and reduced tissue strength.

Mesenchymal stem cell transplantation improves biomechanical properties of vaginal tissue following full-thickness incision in aged rats.

Pelvic organ prolapse (POP) is common among post-menopausal women and is associated with bladder, bowel, and sexual dysfunction. Surgical repair with the patients' native tissues is sub-optimal with high reoperation rates, potentially due to diminished age-related healing. We demonstrate that systemic transplantation of mesenchymal stem cells (MSCs) improves healing of full-thickness vaginal incision in the vaginal wall of old rats, as suggested by both histological and functional analysis. Transplanted MSCs homed and survived at the surgical vaginal site. Attenuation of the injury-induced inflammatory response, increased angiogenesis, and reduced matrix metalloproteinase 9 expression were observed at the surgical site of transplanted rats. Most importantly, the functional biomechanical properties of the healed vagina, at day 30 post-injury, were improved in MSC-transplanted, compared with sham-operated non-transplanted, old rats. These results may pave the way to further translational studies toward clinical transplantation of MSCs adjuvant to POP repair for the improvement of surgical outcome.

Astrocytes support hippocampal-dependent memory and long-term potentiation via interleukin-1 signaling.

Recent studies indicate that astrocytes play an integral role in neural and synaptic functioning. To examine the implications of these findings for neurobehavioral plasticity we investigated the involvement of astrocytes in memory and long-term potentiation (LTP), using a mouse model of impaired learning and synaptic plasticity caused by genetic deletion of the interleukin-1 receptor type I (IL-1RI). Neural precursor cells (NPCs), derived from either wild type (WT) or IL-1 receptor knockout (IL-1rKO) neonatal mice, were labeled with bromodeoxyuridine (BrdU) and transplanted into the hippocampus of either IL-1rKO or WT adult host mice. Transplanted NPCs survived and differentiated into astrocytes (expressing GFAP and S100ß), but not to neurons or oligodendrocytes. The NPCs-derived astrocytes from WT but not IL-1rKO mice displayed co-localization of GFAP with the IL-1RI. Four to twelve weeks post-transplantation, memory functioning was examined in the fear-conditioning and the water maze paradigms and LTP of perforant path-dentate gyrus synapses was assessed in anesthetized mice. As expected, IL-1rKO mice transplanted with IL-1rKO cells or sham operated displayed severe memory disturbances in both paradigms as well as a marked impairment in LTP. In contrast, IL-1rKO mice transplanted with WT NPCs displayed a complete rescue of the impaired memory functioning as well as partial restoration of LTP. These findings indicate that astrocytes play a critical role in memory functioning and LTP, and specifically implicate astrocytic IL-1 signaling in these processes. The results suggest novel conceptualization and therapeutic targets for neuropsychiatric disorders characterized by impaired astrocytic functioning concomitantly with disturbed memory and synaptic plasticity.

Systemically transplanted mesenchymal stem cells induce vascular-like structure formation in a rat model of vaginal injury.

The beneficial effect of mesenchymal stem cells (MSCs) on wound healing is mostly attributed to a trophic effect that promotes angiogenesis. Whether MSCs can contribute to the formation of new blood vessels by direct differentiation is still controversial. Pelvic floor dysfunction (PFD) is a group of disorders that negatively affect the quality of women's lives. Traditional vaginal surgical repair provides disappointing anatomical outcome. Stem cell transplantation may be used to supplement surgery and improve its outcome. Here we aimed to examine the engraftment, survival, differentiation and angiogenic effect of transplanted MSCs in a vaginal injury rat model. MSCs were obtained from the bone marrow of Sprague Drawley (SD) rats, expanded and characterized in vitro. The MSCs expressed CD90 and CD29, did not express CD45, CD34, CD11b and CD31 and could differentiate into osteogenic, chondrogenic and adipogenic lineages. Cells were labeled with either PKH-26 or GFP and transplanted systemically or locally to female SD rats, just after a standardized vaginal incision was made. Engraftment after local transplantation was less efficient at all-time points compared to systemic administration. In the systemically transplanted animal group, MSCs migrated to the injury site and were present in the healed vagina for at least 30 days. Both systemic and local MSCs transplantation promoted host angiogenesis. Systemically transplanted MSCs created new vascular-like structures by direct differentiation into endothelium. These findings pave the way to further studies of the potential role of MSCs transplantation in improving surgical outcome in women with PFD.

Intrahippocampal transplantation of transgenic neural precursor cells overexpressing interleukin-1 receptor antagonist blocks chronic isolation-induced impairment in memory and neurogenesis.

The proinflammatory cytokine interleukin-1 (IL-1) within the brain is critically involved in mediating the memory impairment induced by acute inflammatory challenges and psychological stress. However, the role of IL-1 in memory impairment and suppressed neurogenesis induced by chronic stress exposure has not been investigated before now. We report here that mice that were isolated for 4 weeks displayed a significant elevation in hippocampal IL-1beta levels concomitantly with body weight loss, specific impairment in hippocampal-dependent memory, and decreased hippocampal neurogenesis. To examine the causal role of IL-1 in these effects, we developed a novel approach for long-term delivery of IL-1 receptor antagonist (IL-1ra) into the brain, using transplantation of neural precursor cells (NPCs), obtained from neonatal mice with transgenic overexpression of IL-1ra (IL-1raTG) under the glial fibrillary acidic protein promoter. Four weeks following intrahippocampal transplantation of IL-1raTG NPCs labeled with PKH-26, the transplanted cells were incorporated within the dentate gyrus and expressed mainly astrocytic markers. IL-1ra levels were markedly elevated in the hippocampus, but not in other brain regions, by 10 days and for at least 4 weeks post-transplantation. Transplantation of IL-1raTG NPCs completely rescued the chronic isolation-induced body weight loss, memory impairment, and suppressed hippocampal neurogenesis, compared with isolated mice transplanted with WT cells or sham operated. The transplantation had no effect in group-housed mice. These findings elucidate the role of IL-1 in the pathophysiology of chronic isolation and suggest that transplantation of IL-1raTG NPCs may provide a useful therapeutic procedure for IL-1-mediated memory disturbances in chronic inflammatory and neurological conditions.

Intra-hippocampal transplantation of neural precursor cells with transgenic over-expression of IL-1 receptor antagonist rescues memory and neurogenesis impairments in an Alzheimer's disease model.

Ample evidence implicates neuroinflammatory processes in the etiology and progression of Alzheimer's disease (AD). To assess the specific role of the pro-inflammatory cytokine interleukin-1 (IL-1) in AD we examined the effects of intra-hippocampal transplantation of neural precursor cells (NPCs) with transgenic over-expression of IL-1 receptor antagonist (IL-1raTG) on memory functioning and neurogenesis in a murine model of AD (Tg2576 mice). WT NPCs- or sham-transplanted Tg2576 mice, as well as naive Tg2576 and WT mice served as controls. To assess the net effect of IL-1 blockade (not in the context of NPCs transplantation), we also examined the effects of chronic (4 weeks) intra-cerebroventricular (i.c.v.) administration of IL-1ra. We report that 12-month-old Tg2576 mice exhibited increased mRNA expression of hippocampal IL-1ß, along with severe disturbances in hippocampal-dependent contextual and spatial memory as well as in neurogenesis. Transplantation of IL-1raTG NPCs 1 month before the neurobehavioral testing completely rescued these disturbances and significantly increased the number of endogenous hippocampal cells expressing the plasticity-related molecule BDNF. Similar, but less-robust effects were also produced by transplantation of WT NPCs and by i.c.v. IL-1ra administration. NPCs transplantation produced alterations in hippocampal plaque formation and microglial status, which were not clearly correlated with the cognitive effects of this procedure. The results indicate that elevated levels of hippocampal IL-1 are causally related to some AD-associated memory disturbances, and provide the first example for the potential use of genetically manipulated NPCs with anti-inflammatory properties in the treatment of AD.