Bone marrow stromal cells and bone marrow-derived mononuclear cells: Which are suitable as cell source of transplantation for mice infarct brain?

Anti-stroke biologics: from recombinant proteins to stem cells and organoids

The use of biologics in various diseases has dramatically increased in recent years. Stroke, a cerebrovascular disease, is the second most common cause of death, and the leading cause of disability with high morbidity worldwide. For biologics applied in the treatment of acute ischaemic stroke, alteplase is the only thrombolytic agent. Meanwhile, current clinical trials show that two recombinant proteins, tenecteplase and non-immunogenic staphylokinase, are most promising as new thrombolytic agents for acute ischaemic stroke therapy. In addition, stem cell-based therapy, which uses stem cells or organoids for stroke treatment, has shown promising results in preclinical and early clinical studies. These strategies for acute ischaemic stroke mainly rely on the unique properties of undifferentiated cells to facilitate tissue repair and regeneration. However, there is a still considerable journey ahead before these approaches become routine clinical use. This includes optimising cell delivery methods, determining the ideal cell type and dosage, and addressing long-term safety concerns. This review introduces the current or promising recombinant proteins for thrombolysis therapy in ischaemic stroke and highlights the promise and challenges of stem cells and cerebral organoids in stroke therapy.

Efficacy and Safety of Bone Marrow Derived Stem Cell Therapy for Ischemic Stroke: Evidence from Network Meta-analysis

BACKGROUND

Several types of stem cells are available for the treatment of stroke patients. However, the optimal type of stem cell remains unclear.

OBJECTIVE

To analyze the effects of bone marrow-derived stem cell therapy in patients with ischemic stroke by integrating all available direct and indirect evidence in network meta-analyses.

METHODS

We searched several databases to identify randomized clinical trials comparing clinical outcomes of bone marrow-derived stem cell therapy vs. conventional treatment in stroke patients. Pooled relative risks (RRs) and mean differences (MDs) were reported. The surface under the cumulative ranking (SUCRA) was used to rank the probabilities of each agent regarding different outcomes.

RESULTS

Overall, 11 trials with 576 patients were eligible for analysis. Three different therapies, including mesenchymal stem cells (MSCs), mononuclear stem cells (MNCs), and multipotent adult progenitor cells (MAPCs), were assessed. The direct analysis demonstrated that stem cell therapy was associated with significantly reduced all-cause mortality rates (RR 0.55, 95% CI 0.33 to 0.93; I2=0%). Network analysis demonstrated MSCs ranked first in reducing mortality (RR 0.42, 95% CrI 0.15 to 0.86) and improving modified Rankin Scale score (MD -0.59 95% CI -1.09 to -0.09), with SUCRA values 80%, and 98%, respectively. Subgroup analysis showed intravenous transplantation was superior to conventional therapy in reducing all-cause mortality (RR 0.53, 95% CrI 0.29 to 0.88).

CONCLUSION

Using stem cell transplantation was associated with reduced risk of death and improved functional outcomes in patients with ischemic stroke. Additional large trials are warranted to provide more conclusive evidence.

Clinical Trials of Stem Cell Therapy for Cerebral Ischemic Stroke

Despite recent developments in innovative treatment strategies, stroke remains one of the leading causes of death and disability worldwide. Stem cell therapy is currently attracting much attention due to its potential for exerting significant therapeutic effects on stroke patients. Various types of cells, including bone marrow mononuclear cells, bone marrow/adipose-derived stem/stromal cells, umbilical cord blood cells, neural stem cells, and olfactory ensheathing cells have enhanced neurological outcomes in animal stroke models. These stem cells have also been tested via clinical trials involving stroke patients. In this article, the authors review potential molecular mechanisms underlying neural recovery associated with stem cell treatment, as well as recent advances in stem cell therapy, with particular reference to clinical trials and future prospects for such therapy in treating stroke.

Serial Cerebral Metabolic Changes in Patients With Ischemic Stroke Treated With Autologous Bone Marrow Derived Mononuclear Cells

Purpose: Cell-based therapy offers new opportunities for the development of novel treatments to promote tissue repair, functional restoration, and cerebral metabolic balance. N-acetylasperate (NAA), Choline (Cho), and Creatine (Cr) are three major metabolites seen on proton magnetic resonance spectroscopy (MRS) that play a vital role in balancing the biochemical processes and are suggested as markers of recovery. In this preliminary study, we serially monitored changes in these metabolites in ischemic stroke patients who were treated with autologous bone marrow-derived mononuclear cells (MNCs) using non-invasive MRS.

Materials and Methods: A sub-group of nine patients (3 male, 6 female) participated in a serial MRS study, as part of a clinical trial on autologous bone marrow cell therapy in acute ischemic stroke. Seven to ten million mononuclear cells were isolated from the patient's bone marrow and administered intravenously within 72 h of onset of injury. MRS data were obtained at 1, 3, and 6 months using a whole-body 3.0T MRI. Single voxel point-resolved spectroscopy (PRESS) was obtained within the lesion and contralesional gray matter. Spectral analysis was done using TARQUIN software and absolute concentration of NAA, Cho, and Cr was determined. National Institute of Health Stroke Scale (NIHSS) was serially recoreded. Two-way analysis of variance was performed and p < 0.05 considered statistically significant.

Results: All metabolites showed statistically significant or clear trends toward lower ipsilesional concentrations compared to the contralesional side at all time points. Statistically significant reductions were found in ipsilesional NAA at 1M and 3M, Cho at 6M, and Cr at 1M and 6M (p < 0.03), compared to the contralesional side. Temporally, ipsilesional NAA increased between 3M and 6M (p < 0.01). On the other hand, ipsilesional Cho showed continued decline till 6M (p < 0.01). Ipsilesional Cr was stable over time. Contralesional metabolites were relatively stable over time, with only Cr showing a reduction 3M (p < 0.02). There was a significant (p < 0.03) correlation between ipsilesional NAA and NIHSS at 3M follow-up.

Conclusion: Serial changes in metabolites suggest that MRS can be applied to monitor therapeutic changes. Post-treatment increasing trends of NAA concentration and significant correlation with NIHSS support a potential therapeutic effect.

Diabetic Ephrin-B2-Stimulated Peripheral Blood Mononuclear Cells Enhance Poststroke Recovery in Mice

Clinical trials of cell therapy in stroke favor autologous cell transplantation. To date, feasibility studies have used bone marrow-derived mononuclear cells, but harvesting bone marrow cells is invasive thus complicating bedside treatment. We investigated the therapeutic potential of peripheral blood-derived mononuclear cells (PB-MNC) harvested from diabetic patients and stimulated by ephrin-B2 (PB-MNC+) (500,000 cells), injected intravenously 18–24 hours after induced cerebral ischemia in mice. Infarct volume, neurological deficit, neurogenesis, angiogenesis, and inflammation were investigated as were the potential mechanisms of PB-MNC+ cells in poststroke neurorepair. At D3, infarct volume was reduced by 60% and 49% compared to unstimulated PB-MNC and PBS-treated mice, respectively. Compared to PBS, injection of PB-MNC+ increased cell proliferation in the peri-infarct area and the subventricular zone, decreased microglia/macrophage cell density, and upregulated TGF-β expression. At D14, microvessel density was decreased and functional recovery was enhanced compared to PBS-treated mice, whereas plasma levels of BDNF, a major regulator of neuroplasticity, were increased in mice treated with PB-MNC+ compared to the other two groups. Cell transcriptional analysis showed that ephrin-B2 induced phenotype switching of PB-MNC by upregulating genes controlling cell proliferation, inflammation, and angiogenesis, as confirmed by adhesion and Matrigel assays. Conclusions. This feasibility study suggests that PB-MNC+ transplantation poststroke could be a promising approach but warrants further investigation. If confirmed, this rapid, noninvasive bedside cell therapy strategy could be applied to stroke patients at the acute phase.

Effects of bone marrow mesenchymal stem cells (BM-MSCs) on rat pial microvascular remodeling after transient middle cerebral artery occlusion

Previous studies have shown that the pial microcirculation remodeling improves neurological outcome after middle cerebral artery occlusion (MCAO), accompanied by higher expression of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS), modulating in vivo angiogenesis. This study was aimed to assess the effects of bone marrow mesenchymal stem cells (BM-MSCs) infused after MCAO on rat pial microcirculation. Animals were subjected to 2 h MCAO followed by BM-MSCs infusion into internal carotid artery. Pial microcirculation was observed at different reperfusion times by fluorescence microscopy. Geometric characteristics of arteriolar networks, permeability increase, leukocyte adhesion, perfused capillary density, VEGF, and endothelial nitric oxide synthase (e-NOS) expression were evaluated. Green fluorescent protein (GFP)-BM-MSCs were used to evaluate their distribution and cell phenotype development during reperfusion. BM-MSCs stimulated a geometric rearrangement of pial networks with formation of new anastomotic vessels sprouting from preexistent arterioles in the penumbra at 7-14-28 days of reperfusion. At the same time VEGF and eNOS expression increased. GFP-BM-MSCs appear to be involved in endothelial and smooth muscle cell programming in the infarcted area. In conclusion, transient MCAO induced pial vascular remodeling characterized by arteriolar anastomotic arcades (originated from preexistent arterioles in penumbra area) able to overlap the ischemic core supplying blood to the neuronal tissue. BM-MSCs appear to accelerate angiogenic processes facilitating new vessel formation; this mechanism was promoted by an increase in VEGF and eNOS expression.

CXCR4(+)CD45(-) BMMNC subpopulation is superior to unfractionated BMMNCs for protection after ischemic stroke in mice

Cell-based therapy is considered to be a promising therapeutic strategy for stroke treatment. Although unfractionated bone marrow mononuclear cells (BMMNCs) have been tried in both preclinical and clinical trials, the effective subpopulations need to be identified. In this study, we used fluorescence-activated cell sorting to harvest the CXCR4(+)CD45(+) and CXCR4(+)CD45(-) BMMNC subpopulations from transgenic mice that express enhanced green fluorescent protein. We then allogeneically grafted unfractionated BMMNCs or a subpopulation into mice subjected to transient middle cerebral artery occlusion (tMCAO) and compared the effects on stroke outcomes. We found that CXCR4(+)CD45(-) BMMNCs, but not CXCR4(+)CD45(+) BMMNCs, more effectively reduced infarction volume and neurologic deficits than did unfractionated BMMNCs. Brain tissue from the ischemic hemisphere of mice treated with CXCR4(+)CD45(-) BMMNCs had higher levels of vascular endothelial growth factor and lower levels of TNF-α than did tissue from mice treated with unfractionated BMMNCs. In contrast, CXCR4(+)CD45(+) BMMNCs showed an increase in TNF-α. Additionally, CXCR4(+)CD45(+) and CXCR4(+)CD45(-) populations exhibited more robust migration into the lesion areas and were better able to express cell-specific markers of different linages than were the unfractionated BMMNCs. Endothelial and astrocyte cell markers did not colocalize with eGFP(+) cells in the brains of tMCAO mice that received CXCR4(+)CD45(+) BMMNCs. In vitro, the CXCR4(+)CD45(-) BMMNCs expressed significantly more Oct-4 and Nanog mRNA than did the unfractionated BMMNCs. However, we did not detect gene expression of these two pluripotent markers in CXCR4(+)CD45(+) BMMNCs. Taken together, our study shows for the first time that the CXCR4(+)CD45(-) BMMNC subpopulation is superior to unfractionated BMMNCs in ameliorating cerebral damage in a mouse model of tMCAO and could represent a new therapeutic approach for stroke treatment.

Use of FK506 and bone marrow mesenchymal stem cells for rat hind limb allografts

Dark Agouti rat donor hind limbs were orthotopically transplanted into Lewis rat recipients to verify the effects of bone marrow mesenchymal stem cells on neural regeneration and functional recovery of allotransplanted limbs in the microenvironment of immunotolerance. bone marrow mesenchymal stem cells were intramuscularly (gluteus maximus) injected with FK506 (tacrolimus) daily, and were transplanted to the injured nerves. Results indicated that the allograft group not receiving therapy showed severe rejection, with transplanted limbs detaching at 10 days after transplantation with complete necrosis. The number of myelinated axons and Schwann cells in the FK506 and FK506 + bone marrow mesenchymal stem cells groups were significantly increased. We observed a lesser degree of gastrocnemius muscle degeneration, and increased polymorphic fibers along with other pathological changes in the FK506 + bone marrow mesenchymal stem cells group. The FK506 + bone marrow mesenchymal stem cells group showed significantly better recovery than the autograft and FK506 groups. The results demonstrated that FK506 improved the immune microenvironment. FK506 combined with bone marrow mesenchymal stem cells significantly promoted sciatic nerve regeneration, and improved sensory recovery and motor function in hind limb allotransplant.

Neurorestorative therapy for stroke

Ischemic stroke is responsible for many deaths and long-term disability world wide. Development of effective therapy has been the target of intense research. Accumulating preclinical literature has shown that substantial functional improvement after stroke can be achieved using subacutely administered cell-based and pharmacological therapies. This review will discuss some of the latest findings on bone marrow-derived mesenchymal stem cells (BMSCs), human umbilical cord blood cells, and off-label use of some pharmacological agents, to promote recovery processes in the sub-acute and chronic phases following stroke. This review paper also focuses on molecular mechanisms underlying the cell-based and pharmacological restorative processes, which enhance angiogenesis, arteriogenesis, neurogenesis, and white matter remodeling following cerebral ischemia as well as an analysis of the interaction/coupling among these restorative events. In addition, the role of microRNAs mediating the intercellular communication between exogenously administered cells and parenchymal cells, and their effects on the regulation of angiogenesis and neuronal progenitor cell proliferation and differentiation, and brain plasticity after stroke are described.

Effect of repeated allogeneic bone marrow mononuclear cell transplantation on brain injury following transient focal cerebral ischemia in rats

AIMS

Transplantation of bone marrow mononuclear cells (BMMCs) exerts neuroprotection against cerebral ischemia. We examined the therapeutic timepoint of allogeneic BMMC transplantation in a rat model of focal cerebral ischemia, and determined the effects of repeated transplantation outside the therapeutic window.

MAIN METHODS

Male Sprague-Dawley rats were subjected to 90 minute focal cerebral ischemia, followed by intravenous administration of 1 × 10(7) allogeneic BMMCs or vehicle at 0, 3 or 6 h after reperfusion or 2 × 10(7) BMMCs 6 h after reperfusion. Other rats administered 1 × 10(7) BMMCs at 6 h after reperfusion received additional BMMC transplantation or vehicle 9 h after reperfusion. Infarct volumes, neurological deficit scores and immunohistochemistry were evaluated 24 or 72 h after reperfusion.

KEY FINDINGS

Infarct volumes at 24 h were significantly decreased in transplantation rats at 0 and 3 h, but not at 6 h, after reperfusion, compared to vehicle-treatment. Even high dose BMMC transplantation at 6h after reperfusion was ineffective. Repeated BMMC transplantation at 6 and 9h after reperfusion reduced infarct volumes and significantly improved neurological deficit scores at 24 and 72 h. Immunohistochemistry showed repeated BMMC transplantation reduced ionized calcium-binding adapter molecule 1, 4-hydroxy-2-nonenal and 8-hydroxydeoxyguanosine expression at 24 and 72 h after reperfusion.

SIGNIFICANCE

Intravenous allogeneic BMMCs were neuroprotective following transient focal cerebral ischemia, and the therapeutic time window of BMMC transplantation was >3 h and <6 h after reperfusion in this model. Repeated transplantation at 6 and 9 h after reperfusion suppressed inflammation and oxidative stress in ischemic brains, resulting in improved neuroprotection.

Effect of the bone marrow cell transplantation on elevated plus-maze performance in hippocampal-injured mice

Several reports have shown that the hippocampus plays an important role in different aspects of the emotional control. There is evidence that lesions in this structure cause behavioral disinhibition, with reduction of reactions expressing fear and anxiety. Thus, to portray the aptitude of cell therapy to abrogate injuries of hippocampal tissue, we examined the behavioral effects of bone marrow mononuclear cells (BMMCs) transplantation on C57BL/6 mice that had the hippocampus damaged by electrolytic lesion. For this purpose, mice received, seven days after bilateral electrolytic lesion in the dorsal hippocampus, culture medium or BMMCs expressing the enhanced green fluorescent protein (EGFP) transgene. One week after transplantation, animals were tested in the elevated plus-maze (EPM). On the whole, three assessment sessions in the EPM were carried out, with seven days separating each trial. Thirty-five days after the induction of injury, mice were sacrificed and their brains removed for immunohistochemistry. The behavioral evaluation showed that the hippocampal lesion caused disinhibition, an effect which was slightly lessened, from the second EPM test, in transplanted subjects. On the other hand, immunohistochemical data revealed an insignificant presence of EGFP(+) cells inside the brains of injured mice. In view of such scenario, we hypothesized that the subtle rehabilitation of the altered behavior might be a result from a paracrine effect from the transplanted cells. This might have been caused by the release of bioactive factors capable of boosting endogenous recuperative mechanisms for a partial regaining of the hippocampal functions.

Multipotent mesenchymal stromal cells increase tPA expression and concomitantly decrease PAI-1 expression in astrocytes through the sonic hedgehog signaling pathway after stroke (in vitro study)

Multipotent mesenchymal stromal cells (MSCs) increase tissue plasminogen activator (tPA) activity in astrocytes of the ischemic boundary zone, leading to increased neurite outgrowth in the brain. To probe the mechanisms that underlie MSC-mediated activation of tPA, we investigated the morphogenetic gene, sonic hedgehog (Shh) pathway. In vitro oxygen and glucose deprivation and coculture of astrocytes and MSCs were used to mimic an in vivo ischemic condition. Both real-time-PCR and western blot showed that MSC coculture significantly increased the Shh level and concomitantly increased tPA and decreased plasminogen activator inhibitor 1 (PAI-1) levels in astrocytes. Inhibiting the Shh signaling pathway with cyclopamine blocked the increase of tPA and the decrease of PAI-1 expression in astrocytes subjected to MSC coculture or recombinant mouse Shh (rm-Shh) treatment. Both MSCs and rm-Shh decreased the transforming growth factor-β1 level in astrocytes, and the Shh pathway inhibitor cyclopamine reversed these decreases. Both Shh-small-interfering RNA (siRNA) and Glil-siRNA downregulated Shh and Gli1 (a key mediator of the Shh transduction pathway) expression in cultured astrocytes and concomitantly decreased tPA expression and increased PAI-1 expression in these astrocytes after MSC or rm-Shh treatment. Our data indicate that MSCs increase astrocytic Shh, which subsequently increases tPA expression and decreases PAI-1 expression after ischemia.

Comparison of bone marrow mesenchymal stem cells with bone marrow-derived mononuclear cells for treatment of diabetic critical limb ischemia and foot ulcer: a double-blind, randomized, controlled trial

AIMS

To identify better cells for the treatment of diabetic critical limb ischemia (CLI) and foot ulcer in a pilot trial.

METHODS

Under ordinary treatment, the limbs of 41 type 2 diabetic patients with bilateral CLI and foot ulcer were injected intramuscularly with bone marrow mesenchymal stem cells (BMMSCs), bone marrow-derived mononuclear cells (BMMNCs), or normal saline (NS).

RESULTS

The ulcer healing rate of the BMMSC group was significantly higher than that of BMMNCs at 6 weeks after injection (P=0.022), and reached 100% 4 weeks earlier than BMMNC group. After 24 weeks of follow-up, the improvements in limb perfusion induced by the BMMSCs transplantation were more significant than those by BMMNCs in terms of painless walking time (P=0.040), ankle-brachial index (ABI) (P=0.017), transcutaneous oxygen pressure (TcO(2)) (P=0.001), and magnetic resonance angiography (MRA) analysis (P=0.018). There was no significant difference between the groups in terms of pain relief and amputation and there was no serious adverse events related to both cell injections.

CONCLUSIONS

BMMSCs therapy may be better tolerated and more effective than BMMNCs for increasing lower limb perfusion and promoting foot ulcer healing in diabetic patients with CLI.

Increasing tPA activity in astrocytes induced by multipotent mesenchymal stromal cells facilitate neurite outgrowth after stroke in the mouse

We demonstrate that tissue plasminogen activator (tPA) and its inhibitors contribute to neurite outgrowth in the central nervous system (CNS) after treatment of stroke with multipotent mesenchymal stromal cells (MSCs). In vivo, administration of MSCs to mice subjected to middle cerebral artery occlusion (MCAo) significantly increased activation of tPA and downregulated PAI-1 levels in the ischemic boundary zone (IBZ) compared with control PBS treated mice, concurrently with increases of myelinated axons and synaptophysin. In vitro, MSCs significantly increased tPA levels and concomitantly reduced plasminogen activator inhibitor 1 (PAI-1) expression in astrocytes under normal and oxygen and glucose deprivation (OGD) conditions. ELISA analysis of conditioned medium revealed that MSCs stimulated astrocytes to secrete tPA. When primary cortical neurons were cultured in the conditioned medium from MSC co-cultured astrocytes, these neurons exhibited a significant increase in neurite outgrowth compared to conditioned medium from astrocytes alone. Blockage of tPA with a neutralizing antibody or knock-down of tPA with siRNA significantly attenuated the effect of the conditioned medium on neurite outgrowth. Addition of recombinant human tPA into cortical neuronal cultures also substantially enhanced neurite outgrowth. Collectively, these in vivo and in vitro data suggest that the MSC mediated increased activation of tPA in astrocytes promotes neurite outgrowth after stroke.