Stem cells to help produce functional recovery in stroke

Other than a source of hematopoietic stem cells, bone marrow has been discovered to contain stem cells of non-hematopoietic tissues that could help produce functional recovery in stroke. These cells, referred to as mesenchymal stem cells or stromal cells, can potentially differentiate into a variety of cell types such as adipocytes, chodrocytes, osteoblasts, or myoblasts. Recently, marrow stromal cells have also been demonstrated to differentiate into neural cells under experimental culture conditions, and in vivo studies have shown that bone marrow cells delivered intraperitoneally or intravenously to mice can migrate into the brain and exhibit neuronal phenotypes. Human bone marrow stem cells transplanted in ischemic brain of rats have been shown to express neural markers and reduce neurological deficits.

In previous studies, it was shown that human umbilical cord blood cells, another source of hematopoietic stem cells, were able to differentiate into neurons in vitro and when transplanted into the developing rat brain. Based on these findings, human umbilical cord blood cells were transplanted into models of stroke and traumatic brain injury. There was a reduction in behavioural deficits and this was associated with the expression of neuronal and glial markers by a small fraction of the transplanted human umbilical cord blood cells.
Because of the robust behavioural effects seen in the present transplanted stroke animals, it seems doubtful that the mechanism of observed functional improvement involves “cell replacement”; it is more likely that the cells act as “trophic factories”, supplying necessary trophic factors to the injured brain.

There are many unanswered questions though. Which cell type, whether it is coming from human umbilical cord, mobilised peripheral blood cells, multipotent adult progenitor cells or marrow stromal cells is optimal for stroke therapy? What is the optimal transplantation delivery route: intravenous, intra-arterial, intracerebral? What is the mechanism of improved functional outcome? How do these cells “home” to the area of injury? Can this homing be modulated? The present finging solicits future studies to address these critical issues that will guide the design of clinical trials.
Certainly, mobilised peripheral progenitor cells have many advantages: they are autologous, relatively easy to isolate, and may not even need to be isolated.

Even though the use of stem cells even when they come from cord blood collection has been a very controversial topic over the years, it seems that they could be used in many ways in basic research as well as in clinical research to help human beings cure deseases like leukaemia, help produce functional recovery in stroke or even more.