In last two decades, stem cell science has rapidly evolved and hold potential to significantly impact the healthcare industry. Stem cells being naive cells are self renewing cells with the ability to differentiate into several cell lineages including cartilage, adipose, bone tissues etc. These unique properties of stem cells have raised hopes in clinical trials for the application of MSCs in regenerative therapies including degenerative disorders and anti aging treatment.
However in some animal studies and clinical trials, ambiguity has been observed in results; sometime Mesenchymal stem cell therapies being ineffective or only temporarily effective could be due to suboptimal application of stem cells. The critical challenge for translating stem cell therapy to the clinic is to deliver safe and effective dose of cells to patients. When stem cells are injected to body, the major question arises where the cells go and whether the cells can survive, bind and engraft to damaged tissues.
After injecting stem cells to body, these cells are destined to proliferate and differentiate into specific cells for enabling repair or regenerate organ. The fate of cells is determined by various extrinsic cues or signals provided by the surrounding environment and by their location in a body. In a research article published in Nature, Mamidi et al. provided insight on how cell location and exposure to certain external cues can affect cells in the developing pancreas give rise to β-cells that make the protein insulin.
Researchers worldwide are doing trials to find out the best possible way to get cells into the human body. One of the most common and convenient mode of MSC transplantation is intravenous delivery. However studies have shown that intravenous administration of cells often results in low levels of cell integration into host tissue. With intravenous administration of cells, majority of cells initially traffic to the liver and spleen, bone marrow and skin. Only a small signal is detected in the myocardium with intravenous delivery suggesting that there is minimal uptake in heart. This will subsequently influence the outcome of treatment specially disease related to specific organs.
In order to have maximized therapeutic benefit, it is important to have site specific delivery of stem cells. A recent study compared three methods of delivering cells to the spinal cord- lumbar puncture, intravenous injection and direct injection into the spine and found that the most invasive method, direct injection, gave the best result, followed by lumbar puncture and intravenous injection. Site specific injections have the advantage of precise localization of the cells, where their requirement is most. Researchers hope that new techniques incorporating biomaterials, culturing strategies, surgical devices and patches will translate into better stem cell delivery methods that will help cells to survive and integrate appropriately into the human body, as well as limiting their unpredictable behaviour.
Success of any therapy is dependant of site specific action and stem cells are no exception to this. The exact delivery location of stem cells helps stem cells to home at required location and create a specific niche for themselves. This will not only save the time of stem cells migration to diseased organ but will also help to achieve the result in smaller dose. Thus a strong need to have optimum cell delivery route appropriate for specific disease condition that provide better regeneration benefit with minimal side effects.