Paracrine Interactions Involved in Human Induced Pluripotent Stem Cells Differentiation into Chondrocytes

The role of exosomes in pathogenesis and the therapeutic efficacy of mesenchymal stem cell-derived exosomes against Parkinson's disease

Parkinson's disease (PD) is a chronic, progressive, neurodegenerative disease. The predominant pathology of PD is the loss of dopaminergic cells in the substantia nigra. Cell transplantation is a strategy with significant potential for treating PD; mesenchymal stem cells (MSCs) are a tremendous therapeutic cell source because they are easily accessible. MSC-derived exosomes with potential protective action in lesioned sites serve as an essential promoter of neuroprotection, and neurodifferentiation, by modulating neural stem cells, neurons, glial cells, and axonal growth in vitro and in vivo environments. The biological properties of MSC-derived exosomes have been proposed as a beneficial tool in different pathological conditions, including PD. Therefore, in this review, we assort the current understanding of MSC-derived exosomes as a new possible therapeutic strategy for PD by providing an overview of the potential role of miRNAs as a component of exosomes in the cellular and molecular basis of PD.

Cell Interplay in Osteoarthritis

Osteoarthritis (OA) is a common chronic disease and a significant health concern that needs to be urgently solved. OA affects the cartilage and entire joint tissues, including the subchondral bone, synovium, and infrapatellar fat pads. The physiological and pathological changes in these tissues affect the occurrence and development of OA. Understanding complex crosstalk among different joint tissues and their roles in OA initiation and progression is critical in elucidating the pathogenic mechanism of OA. In this review, we begin with an overview of the role of chondrocytes, synovial cells (synovial fibroblasts and macrophages), mast cells, osteoblasts, osteoclasts, various stem cells, and engineered cells (induced pluripotent stem cells) in OA pathogenesis. Then, we discuss the various mechanisms by which these cells communicate, including paracrine signaling, local microenvironment, co-culture, extracellular vesicles (exosomes), and cell tissue engineering. We particularly focus on the therapeutic potential and clinical applications of stem cell-derived extracellular vesicles, which serve as modulators of cell-to-cell communication, in the field of regenerative medicine, such as cartilage repair. Finally, the challenges and limitations related to exosome-based treatment for OA are discussed. This article provides a comprehensive summary of key cells that might be targets of future therapies for OA.

Tribbles homolog 2 (Trib2), a pseudo serine/threonine kinase in tumorigenesis and stem cell fate decisions

The family of Tribbles proteins play many critical nonenzymatic roles and regulate a wide range of key signaling pathways. Tribbles homolog 2 (Trib2) is a pseudo serine/threonine kinase that functions as a scaffold or adaptor in various physiological and pathological processes. Trib2 can interact with E3 ubiquitin ligases and control protein stability of downstream effectors. This protein is induced by mitogens and enhances the propagation of several cancer cells, including myeloid leukemia, liver, lung, skin, bone, brain, and pancreatic. Thus, Trib2 can be a predictive and valuable biomarker for the diagnosis and treatment of cancer. Recent studies have illustrated that Trib2 plays a major role in cell fate determination of stem cells. Stem cells have the capacity to self-renew and differentiate into specific cell types. Stem cells are important sources for cell-based regenerative medicine and drug screening. Trib2 has been found to increase the self-renewal ability of embryonic stem cells, the reprogramming efficiency of somatic cells, and chondrogenesis. In this review, we will focus on the recent advances of Trib2 function in tumorigenesis and stem cell fate decisions.

iPSCs in Modeling and Therapy of Osteoarthritis

Osteoarthritis (OA) belongs to chronic degenerative disorders and is often a leading cause of disability in elderly patients. Typically, OA is manifested by articular cartilage erosion, pain, stiffness, and crepitus. Currently, the treatment options are limited, relying mostly on pharmacological therapy, which is often related to numerous complications. The proper management of the disease is challenging because of the poor regenerative capacity of articular cartilage. During the last decade, cell-based approaches such as implantation of autologous chondrocytes or mesenchymal stem cells (MSCs) have shown promising results. However, the mentioned techniques face their hurdles (cell harvesting, low proliferation capacity). The invention of induced pluripotent stem cells (iPSCs) has created new opportunities to increase the efficacy of the cartilage healing process. iPSCs may represent an unlimited source of chondrocytes derived from a patient's somatic cells, circumventing ethical and immunological issues. Aside from the regenerative potential of iPSCs, stem cell-derived cartilage tissue models could be a useful tool for studying the pathological process of OA. In our recent article, we reviewed the progress in chondrocyte differentiation techniques, disease modeling, and the current status of iPSC-based regenerative therapy of OA.

Differentiation of human induced pluripotent stem cells into erythroid cells

During the last years, several strategies have been made to obtain mature erythrocytes or red blood cells (RBC) from the bone marrow or umbilical cord blood (UCB). However, UCB-derived hematopoietic stem cells (HSC) are a limited source and in vitro large-scale expansion of RBC from HSC remains problematic. One promising alternative can be human pluripotent stem cells (PSCs) that provide an unlimited source of cells. Human PSCs, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), are self-renewing progenitors that can be differentiated to lineages of ectoderm, mesoderm, and endoderm. Several previous studies have revealed that human ESCs can differentiate into functional oxygen-carrying erythrocytes; however, the ex vivo expansion of human ESC-derived RBC is subjected to ethical concerns. Human iPSCs can be a suitable therapeutic choice for the in vitro/ex vivo manufacture of RBCs. Reprogramming of human somatic cells through the ectopic expression of the transcription factors (OCT4, SOX2, KLF4, c-MYC, LIN28, and NANOG) has provided a new avenue for disease modeling and regenerative medicine. Various techniques have been developed to generate enucleated RBCs from human iPSCs. The in vitro production of human iPSC-derived RBCs can be an alternative treatment option for patients with blood disorders. In this review, we focused on the generation of human iPSC-derived erythrocytes to present an overview of the current status and applications of this field.

Mesenchymal Stem Cell-Mediated Mitochondrial Transfer: a Therapeutic Approach for Ischemic Stroke

Stroke is the leading cause of death and adult disability worldwide. Mitochondrial dysfunction is one of the hallmarks of stroke-induced neuronal death, and maintaining mitochondrial function is essential in cell survival and neurological progress following ischemic stroke. Stem cell-mediated mitochondrial transfer represents an emerging therapeutic approach for ischemic stroke. Accumulating evidence suggests that mesenchymal stem cells (MSCs) can directly transfer healthy mitochondria to damaged cells, and rescue mitochondrial damage-provoked tissue degeneration. This review summarizes the research on MSCs-mediated mitochondrial transfer as a therapeutic strategy against ischemic stroke.