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Professor Arnold Caplan discussing mesenchymal stem cells at KAVI – ICR on Friday 17th March 2017. The professor of Biology and General Medical Sciences at Case Western Reserve University, Cleveland. He is widely recognised for his leading efforts in the field of cell therapy and regenerative medicine.


If the tip of your finger – including your nail bed and the adjacent joint – is severed, can you regrow it? The short answer is yes.

Arnold Caplan, a professor of biology and general medical sciences (oncology) at Case Western Reserve University in Cleveland, is widely regarded as the father of mesenchymal stem cells. He is also the director of both the skeletal research center and the cellular and molecular basis for aging training programme at Case Western, and has won numerous awards for his research. He has published widely in the spheres of molecular, cellular and developmental biology, and received his PhD from John Hopkins University Medical School in 1966.

On Friday 17th March, curious minds gathered at KAVI – ICR to attend his anticipated talk on mesenchymal stem cells (MSCs). MSCs are cells with the potential to differentiate into fat, muscle, bone and cartilage cells. The International Society for Cellular Therapy further describes them as cells which express a list of specific proteins, and fail to express others.  They can be derived from bone marrow, adipose tissue or the umbilical cord, and are being studied for their therapeutic use.


Mesenchymal stem cell (MSC) differentiation

MSCs can differentiate into mesodermal cells (solid arrows) and also ecto- and endodermal cells (shown with dashed arrows)


KAVI – ICR has successfully harvested umbilical cord blood from nineteen donors so far, and isolated haematopoetic stem cells. Researchers have also cultured mesenchymal stem cells from adipose tissue, Professor Omu Anzala the director of KAVI – ICR reported. “Our aim is to develop cell therapies and bioengineering products,” he said.

Prof Caplan explained that MSCs are in fact interestingly not stem cells as used in the clinical sense. “We chose to name them stem cells because we’ve proved that if you give MSCs the right chemicals, you get different cell types. However, we want MSC to stand for medical signalling cell. It is really a pharmacy. An injury specific drug store,” Prof Caplan explained.

The unique properties attributed to MSCs’ promising therapeutic use in injury and disease are their ability to: differentiate into different cell types – this is useful as a source to replace damaged tissue; promote tissue regeneration and mitigate tissue injury – they release anti-apoptotic (i.e anti-cell death) molecules, preserve cells and form new blood vessels from old ones; and modulate the immune system – they suppress immune responses, making them useful in the treatment of autoimmune diseases and graft-versus-host disease from transplants.

“MSCs are pericytes,” asserted Prof Caplan. Pericytes are cells which lay on capillaries and micro-vessels, and were first named by French physiologist Charles B. Rouget in 1879. Some give rise to muscle, adipocytes, bone and cartilage. If one has a stroke for example and is given MSCs, the cells will stop the bleeding and prompt regeneration of the damaged tissue in the local environment.

The potential use of MSCs is vast. The professor told of MSC therapy in children with cystic fibrosis: human MSCs administered to mice models with cf have been found to secret a molecule called LL37, which kills Pseudomonas aeruginosa, a bacteria responsible for 60% of lung infections in people with cf.

Prof Caplan also discussed MSCs being tested for the treatment of arthritis: the cells make molecules that sit on opiod receptors, therefore eliminating pain in the patient, and reduce the inflammation in the synovial lining, thus reducing swelling. In a Polish study, MSCs were injected into 250 knees with osteoarthritis, and thicker cartilage was observed in 30% of the patients. This effect was seen as soon as 3 months after treatment with MSCs, but was best observed after 6 months.

Other conditions that are candidates for MSC therapy include: liver disease, heart disease, cancers, diabetes, multiple sclerosis, bone and cartilage disease, spinal cord injury, and brain disease.

It is clear that animals have innate regeneration potential; every second, about 3 million red blood cells in our bodies drop dead and are replaced. “It is simply a management problem – MSCs regulate this potential,” Prof Caplan stated.

As with all things, there are important considerations to make when applying MSCs. “[MSCs] have a melanoma binding protein – CD641. If there are melanomas in the blood, we have seen that the MSCs binds to the melanoma, drawing it out of the blood vessel into the bone,” Prof Caplan explained. Once this happens, he said, one has an 85% chance of dying within 2 years. Although MSCs have been found to be generally well tolerated, caution must nonetheless be applied.

“There have been about 700 clinical trials utilising MSCs in the past 25 years,” Prof Caplan stated. Some of these with conflicting results, although this is to be expected with any treatment as there are always individuals or groups that are non-responders or respond differently than others. Clearly, more pre-clinical and clinical trials are needed to further our understanding, and take MSC therapy from bench to bedside.

By Joy Muthure –



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