Stroke treatments have seen some remarkable advances in the past few years. Stem cell treatments for stroke have even seen some successes in clinical trials, showing that stem cell transplantation aimed at neural repair after a stroke is a possible way to ameliorate the effects of stroke.
Now, collaboration between teams of American and Japanese researchers has shown that a newly-identified stem cell has the ability to successfully treat stroke in rats. When administered to rats who have suffered from an experimentally-induced stroke, MUSE or multilineage-differentiating stress-enduring cells induced the regeneration of neurons and resulted in “significant improvements in neurological and motor functions” compared to control groups that were not transplanted with MUSE cells. MUSE cells also do not cause tumors.
The study has increased the number of therapeutic arrows in the quiver of neurologists and neuroscientists and lengthens the list of cells that might one day be considered for human clinical trials if continued pre-clinical tests prove successful. Future clinical studies aimed at regenerating neurological and motor function in patients who have suffered ischemic stroke.
The paper describing this study appeared in a recent issue of Stem Cells (Sept. 2015).
“Muse cells are unique stem cells that are able to self-renew and display high-efficiency for differentiating into neuron-like cells,” explained lead author Dr. Cesar V Borlongan, Distinguished Professor and Vice-Chairman for Research at the University of South Florida (USF) College of Medicine Department of Neurosurgery and Brain Repair and Director of USF’s the Center of Excellence for Aging and Brain Repair. “Unlike mesenchymal stem cells (MSCs) that have previously been used in stem cell transplantation in stroke-related clinical trials, in the present study Muse cells were found to possess functional characteristics of neurons as they attain the attributes of the host microenvironment. When MUSEcells were transplanted into to the brains of rats modeled with stroke, they attained neuronal characteristics.”
MUSE cells are found in many different tissues, including bone marrow, skin and fat. Since these cells can be derived from dermal fibroblasts (a type of connective tissue cell that provides the structural framework for animal tissues and plays a critical role in wound healing), they can be accessed with relative ease, without the need for the painful, invasive procedures required for obtaining other kinds of stem cells. Furthermore, while some stem cells used in stem cell transplantation studies have been found to cause cancer, MUSE cells do not produce tumors and exhibit exceptional tissue repair potential when introduced into the blood stream.
Some researchers think that fetal stem cells might be better candidates for replacing lost neural circuitry. The main reason in favor of fetal stem cells is that they preferentially differentiate into neuronal cells. However, the accessibility to fetal stem cells is limited and, like embryonic stem cells, the immaturity of these cells may present safety issues, such as tumor development. Additionally, the use of fetal and embryonic stem cells has many ethical difficulties to say the least. Since MUSE cells can be derived from adult tissue rather than fetal or embryonic tissue, the ethical quandaries associated with using them is minimal.
Not only do MUSE cells also have the practical advantage of being non-tumorigenic, they are readily accessed commercially and can also be easily collected from patient skin biopsies. MUSE cells also do not have to be “induced,” or genetically manipulated in order to be used, since they already display inherent stem cell properties after isolation. MUSE cells also spontaneously home toward the stroke-damaged sites.
“Ours is the first study to show that human skin fibroblast-derived Muse cells can have neuron-like function, possess an inherent ability to assume ‘stemness’ properties, and to readily differentiate into neural-lineage cells after integration into the stroke brain,” said co-lead author Dr. Mari Dezawa, Department of Stem Cell Biology and Histology, Tohoku University Graduate School of Medicine in Sendai, Japan. “Our results show that Muse cells are a feasible and promising source for cell-based approaches to ischemic stroke therapy.”