Stem cell therapy for the treatment of parasitic infections: is it far away?

The novel treatments based on tissue engineering, cell therapy and nanotechnology for cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) is a global public health issue. Conventional treatments have substantial costs, side effects, and parasite resistance. Due to easy application and inexpensive cost, topical treatment is the optimal approach for CL. It could be used alone or with systemic treatments. Electrospun fibers as drug release systems in treating skin lesions have various advantages such as adjustable drug release rate, maintaining appropriate humidity and temperature, gas exchange, plasticity at the lesion site, similarity with the skin extracellular matrix (ECM) and drug delivery with high efficiency. Hydrogels are valuable scaffolds in the treatment of skin lesions. The important features of hydrogels include preserving unstable drugs from degradation, absorption of wound secretions, high biocompatibility, improving the re-epithelialization of the wound and preventing the formation of scars. One of the issues in local drug delivery systems for the skin is the low permeability of drugs in the skin. Polymeric scaffolds that are designed as microneedle patches can penetrate the skin and overcome this challenge. Also, drug delivery using nanocarriers increases the effectiveness of drugs in lower and more tolerable doses and reduces the toxicity of drugs. The application of cell therapy in the treatment of parasitic and infectious diseases has been widely investigated. The complexity of leishmaniasis treatment requires identifying new treatment options like cell therapy to overcome the disease. Topics investigated in this study include drug delivery systems based on tissue engineering scaffolds, nanotechnology and cell therapy-based studies to reduce the complications of CL.

The Role of Praziquantel in the Prevention and Treatment of Fibrosis Associated with Schistosomiasis: A Review

Schistosomiasis remains a major global public health concern. Currently, the control of this neglected tropical disease still depends on chemotherapy to reduce the prevalence and intensity of the parasite infection. It has been widely accepted that praziquantel is highly effective against all species of Schistosoma, and this agent is virtually the only drug of choice for the treatment of human schistosomiasis. Mass drug administration (MDA) with praziquantel has been shown to be effective in greatly reducing the prevalence and morbidity due to schistosomiasis worldwide. In addition to antischistosomal activity, a large number of experiential and clinical evidence has demonstrated the action of praziquantel against fibrosis caused by S. mansoni and S. japonicum infections through decreasing the expression of fibrotic biomarkers such as α-smooth muscle actin (α-SMA), collagen, matrix metalloproteinase (MMP), and tissue inhibitor of metalloproteinase (TIMP), and inhibiting the expression of proinflammatory cytokines such as interleukin (IL)-6, tumor necrosis factor (TNF)-α, and transforming growth factor (TGF)-β, as well as chemokines, and similar antifibrotic activity was observed in mouse models of fibrosis induced by carbon tetrachloride (CCl4) and concanavalin A (Con-A). In this review, we discuss the role of praziquantel in the prevention and treatment of fibrosis associated with schistosomiasis and the possible mechanisms. We call for randomized, controlled clinical trials to evaluate the efficacy and safety of praziquantel in the treatment of schistosomiasis-induced hepatic fibrosis, and further studies to investigate the potential of praziquantel against fibrosis associated with alcohol consumption, viruses, and toxins seem justified.

Stem Cell-Derived Exosome as Potential Therapeutics for Microbial Diseases

Exosomes, as the smallest extracellular vesicles that carry a cargo of nucleic acids, lipids, and proteins and mediate intercellular communication, have attracted much attention in diagnosis and treatment in the field of medicine. The contents of exosomes vary depending on the cell type and physiological conditions. Among exosomes derived from several cell types, stem cell-derived exosomes (stem cell-Exo) are increasingly being explored due to their immunomodulatory properties, regenerative capacity, anti-inflammatory and anti-microbial functions. Administration of stem cell-Exo, as a cell-free therapy for various diseases, has gained great promise. Indeed, the advantages of exosomes secreted from stem cells outweigh those of their parent cells owing to their small size, high stability, less immunogenicity, no risk of tumorigenesis, and easier condition for storage. Recently, the use of stem cell-Exo has been proposed in the field of microbial diseases. Pathogens including bacteria, viruses, fungi, and parasites can cause various diseases in humans with acute and chronic complications, sometimes resulting in mortality. On the other hand, treatments based on antibiotics and other chemical compounds have many side effects and the strains become resistant to drugs in some cases. Hence, this review aimed to highlight the effect of stem cell-derived extracellular vesicles including stem cell-Exo on microbial diseases. Although most published studies are preclinical, the avenue of clinical application of stem cell-Exo is under way to reach clinical applications. The challenges ahead of this cell-free treatment that might be applied as a therapeutic alternative to stem cells for translation from bench to bed were emphasized, as well.

Mesenchymal stem cells combined with albendazole as a novel therapeutic approach for experimental neurotoxocariasis

Neurotoxocariasis (NT) is a serious condition that has been linked to reduced cognitive function, behavioural alterations and neurodegenerative diseases. Unfortunately, the available drugs to treat toxocariasis are limited with unsatisfactory results, because of the initiation of treatment at late chronic stages after the occurrence of tissue damage and scars. Therefore, searching for a new therapy for this important disease is an urgent necessity. In this context, cytotherapy is a novel therapeutic approach for the treatment of many diseases and tissue damages through the introduction of new cells into the damaged sites. They exert therapeutic effects by their capability of renewal, differentiation into specialized cells, and being powerful immunomodulators. The most popular cell type utilized in cytotherapy is the mesenchymal stem cells (MSCs) type. In the current study, the efficacy of MSCs alone or combined with albendazole was evaluated against chronic brain insults induced by Toxocara canis infection in an experimental mouse model. Interestingly, MSCs combined with albendazole demonstrated a healing effect on brain inflammation, gliosis, apoptosis and significantly reduced brain damage biomarkers (S100B and GFAP) and T. canis DNA. Thus, MSCs would be protective against the development of subsequent neurodegenerative diseases with chronic NT.

hUCMSC-extracellular vesicles downregulated hepatic stellate cell activation and reduced liver injury in S. japonicum-infected mice

Background

Accumulating evidence shows that mesenchymal stem cells (MSCs) have the potential as a cellular therapy avenue for schistosome-induced liver injury. Extracellular vesicles (EVs) are membranous vesicles released by almost all cell types, and EVs produced by MSCs (MSC-EVs) exert therapeutic effects in several disease models. However, the potential of MSC-EVs in schistosomiasis treatment remains unclear.

Methods

Using survival analysis, HE and Masson’s trichrome staining, immunohistochemical, western blot analysis, real-time PCR, and EdU proliferation, we investigated the effects of human umbilical cord MSC-derived EVs (hUCMSC-EVs) on the survival and liver injury in the S. japonicum-infected mice and explored the underlying mechanism.

Results

Here, we found that like hUCMSCs, hUCMSC-EVs significantly ameliorated liver injury and improved the survival of schistosome-infected mice. Indeed, the hUCMSC-EV-mediated alleviation of liver injury is associated with decreased expression of α-smooth muscle actin (α-SMA), collagen 1, and collagen 3. More importantly, we showed that hUCMSC-EVs directly suppressed the proliferation of LX2 (human hepatic stellate cell) in vitro. In addition, hUCMSC-EVs significantly downregulated the activation of LX2 after transforming growth factor-β1 (TGF-β1) treatment.

Conclusion

Our results provided the first evidence that hUCMSC-EVs reduced liver injury in S. japonicum-infected mice, potentially creating new avenues for the treatment of liver damage in schistosomiasis.

Repeated intravenous injection of adipose tissue derived mesenchymal stem cells enhances Th1 immune responses in Leishmania major-infected BALB/c mice

Mesenchymal stem cell (MSCs) therapy are among new strategies that are used to combat infections through immunomodulation. Cell number, route and frequency of injection and the duration of exposure to the infectious agent are of the main factors to determine the effectiveness of cell therapy. The current study was aimed to assess the effect of multiple intravenous (i.v.) injection of adipose tissue derived (AD)-MSCs on immune response of Leishmania (L.) major-infected BALB/c mice. Therefore, infected mice received AD-MSCs four times during the early phase of infection through i.v. route. They were then monitored weekly for footpad swelling and lesion development. Parasite burden, nitric oxide (NO) and cytokine production were measured in the spleen and lymph node 90 days post-infection. Delayed lesion development, significant reduction in footpad swelling and lower parasite burden in the spleen of AD-MSCs-treated mice showed the relative effect of AD-MSCs therapy in the control of L. major dissemination. In addition, MSCs were able to manage direct cytokine responses toward T-helper 1 (Th1). Although the level of interleukin (IL)-10 was still higher than the associated level of tumor necrosis factor (TNF)-α, a shift towards higher level of TNF-α was also observed.

Stem cell therapy: a novel treatment option for cerebral malaria?

Cerebral malaria, a severe form of the disease, is one of the most severe complications of infection with Plasmodium parasites and a leading cause of malaria mortality. Currently available antimalarial therapy has proven insufficient to prevent neurological complications and death in all cases of cerebral malaria. Souza and colleagues observed that transplantation of bone marrow-derived mesenchymal stromal cells (BM-MSCs) increased survival, reduced parasitemia, decreased malaria pigment accumulation in the spleen, liver and kidney, elevated Kupffer cell count in liver, alleviated renal injury and lung inflammation, and improved lung mechanics in an experimental mouse model of cerebral malaria. Although plenty of challenges lie ahead, their findings show the promise of BM-MSC therapy for the treatment of cerebral malaria.

Mesenchymal stromal cell therapy attenuated lung and kidney injury but not brain damage in experimental cerebral malaria

Introduction

Malaria is the most relevant parasitic disease worldwide, and still accounts for 1 million deaths each year. Since current antimalarial drugs are unable to prevent death in severe cases, new therapeutic strategies have been developed. Mesenchymal stromal cells (MSC) confer host resistance against malaria; however, thus far, no study has evaluated the therapeutic effects of MSC therapy on brain and distal organ damage in experimental cerebral malaria.

Methods

Forty C57BL/6 mice were injected intraperitoneally with 5 × 10⁶Plasmodium berghei-infected erythrocytes or saline. After 24 h, mice received saline or bone marrow (BM)-derived MSC (1x10⁵) intravenously and were housed individually in metabolic cages. After 4 days, lung and kidney morphofunction; cerebrum, spleen, and liver histology; and markers associated with inflammation, fibrogenesis, and epithelial and endothelial cell damage in lung tissue were analyzed.

Results

In P. berghei-infected mice, BM-MSCs: 1) reduced parasitemia and mortality; 2) increased phagocytic neutrophil content in brain, even though BM-MSCs did not affect the inflammatory process; 3) decreased malaria pigment detection in spleen, liver, and kidney; 4) reduced hepatocyte derangement, with an increased number of Kupffer cells; 5) decreased kidney damage, without effecting significant changes in serum creatinine levels or urinary flow; and 6) reduced neutrophil infiltration, interstitial edema, number of myofibroblasts within interstitial tissue, and collagen deposition in lungs, resulting in decreased lung static elastance. These morphological and functional changes were not associated with changes in levels of tumor necrosis factor-α, keratinocyte-derived chemokine (KC, a mouse analog of interleukin-8), or interferon-γ, which remained increased and similar to those of P. berghei animals treated with saline. BM-MSCs increased hepatocyte growth factor but decreased VEGF in the P. berghei group.

Conclusions

BM-MSC treatment increased survival and reduced parasitemia and malaria pigment accumulation in spleen, liver, kidney, and lung, but not in brain. The two main organs associated with worse prognosis in malaria, lung and kidney, sustained less histological damage after BM-MSC therapy, with a more pronounced improvement in lung function.

Potential of 5-azacytidine induction decidual stromal cells from maternal human term placenta towards cardiomyocyte-like cells in serum-free medium

Decidual stromal cells (DSCs) from maternal term placenta represent a potential source of cells for the treatment of cardiovascular and graft-versus-host diseases. However, it is not clear whether DSCs could be induced towards cardiomyocyte-like differentiation. We chose the placentas which should bred male new-baby. We isolated DSCs from placenta by tissue adherence. The morphology, immunophenotype, and multi-lineage potential were analyzed. Karyotype analysis (G-band) was performed to determine the source and karyotype stability of DSCs. DSCs were induced by 5-azacytidine. Expression of Myf5, α-cardiac actin, Cardiac troponin T (cTnT) and GAPDH was assessed by PCR, and cTnT expression was also analyzed by immunofluorescence. Karyotype analyses indicated that cells were derived from the maternal matrix. After induction with 5-azacytidine, DSCs expressed the cardiac-specific markers Myf5, myogenin and cTnT, indicating differentiation towards cardiomyocyte-like cells.

Challenges of drug-resistant malaria

Over the past six decades, the drug resistance of Plasmodium falciparum has become an issue of utmost concern. Despite the remarkable progress that has been made in recent years in reducing the mortality rate to about 30% with the scaling-up of vector control, introduction of artemisinin-based combination therapies and other malaria control strategies, the confirmation of artemisinin resistance on the Cambodia–Thailand border threatened all the previous success. This review addresses the global scenario of antimalarial resistance and factors associated with it, with the main emphasis on futuristic approaches like nanotechnology and stem cell therapy that may impede resistant malaria, along with novel medications which are preparing to enter the global antimalarial market. These novel studies are likely to escalate over the coming years and will hopefully help to reduce the burden of malaria.