Stem cell treatments....

[vipinrathee]

Diabetes
Diabetes patients lose the function of insulin-producing beta cells within the pancreas. Human embryonic stem cells may be grown in cell culture and stimulated to form insulin-producing cells that can be transplanted into the patient.
However, clinical success is highly dependent on the development of the following procedures:

• Transplanted cells should proliferate
• Transplanted cells should differentiate in a site-specific manner
• Transplanted cells should survive in the recipient (prevention of transplant rejection)
• Transplanted cells should integrate within the targeted tissue
• Transplanted cells should integrate into the host circuitry and restore function

Brain damage
Stroke and traumatic brain injury lead to cell death, characterized by a loss of neurons and oligodendrocytes within the brain. Healthy adult brains contain neural stem cells which divide to maintain general stem cell numbers, or become progenitor cells. In healthy adult animals, progenitor cells migrate within the brain and function primarily to maintain neuron populations for olfaction (the sense of smell). In pregnancy and after injury, this system appears to be regulated by growth factors and can increase the rate at which new brain matter is formed.Although the reparative process appears to initiate following trauma to the brain, substantial recovery is rarely observed in adults, suggesting a lack of robustness.
Stem cells may also be used to treat brain degeneration, such as in Parkinson's and Alzheimer's disease.

Cancer
The development of gene therapy strategies for treatment of intra-cranial tumours offers much promise, and has shown to be successful in the treatment of some dogs;although research in this area is still at an early stage. Using conventional techniques, brain cancer is difficult to treat because it spreads so rapidly. Researchers at the Harvard Medical School transplanted human neural stem cells into the brain of rodents that received intracranial tumours. Within days, the cells migrated into the cancerous area and produced cytosine deaminase, an enzyme that converts a non-toxic pro-drug into a chemotheraputic agent. As a result, the injected substance was able to reduce the tumor mass by 81 percent. The stem cells neither differentiated nor turned tumorigenic.Some researchers believe that the key to finding a cure for cancer is to inhibit proliferation of cancer stem cells. Accordingly, current cancer treatments are designed to kill cancer cells. However, conventional chemotherapy treatments cannot discriminate between cancerous cells and others. Stem cell therapies may serve as potential treatments for cancer.Research on treating Lymphoma using adult stem cells is underway and has had human trials. Essentially, chemotherapy is used to completely destroy the patients own lymphocytes, and stem cells injected, eventually replacing the immune system of the patient with that of the healthy donor.
Heart damage
Several clinical trials targeting heart disease have shown that adult stem cell therapy is safe, effective, and equally efficient in treating old and recent infarcts.While initial animal studies demonstrated remarkable therapeutic effects, later clinical trials achieved only modest, though statistically significant, improvements. Possible reasons for this discrepancy are patient age, timing of treatment and the recent occurrence of a myocardial infarction. These obstacles may be bypassed by additional treatments to the transplanted stem cells or the patient which increase the effectiveness of the treatment or by optimizing the methodology. Current studies vary greatly in cell procuring techniques, cell types, cell administration timing and procedures, and studied parameters, making it very difficult to make comparisons. Comparative studies are therefore currently needed. Stem cell therapy for treatment of myocardial infarction usually makes use of autologous bone marrow stem cells (a specific type or all), however other types of adult stem cells may be used, such as adipose-derived stem cells. Adult stem cell therapy for treating heart disease was commercially available in at least five continents at the last count (2007).
Possible mechanisms of recovery include:

• Generation of heart muscle cells
• Stimulation of growth of new blood vessels to repopulate damaged heart tissue
• Secretion of growth factors
• Assistance via some other mechanism

It may be possible to have adult bone marrow cells differentiate into heart muscle cells.
The first successful integration of human embryonic-stem-cell-derived cardiomyocytes in guinea pigs (mouse hearts beat too fast) was reported in August 2012. The contraction strength was measured four weeks after the guinea pigs underwent simulated heart attacks and cell treatment. The cells contracted synchronously with the existing cells, but it is unknown if the positive results were produced mainly from paracrine as opposed to direct electromechanical effects from the human cells. Future work will focus on how to get the cells to engraft more strongly around the scar tissue. Whether treatments from embryonic or adult bone marrow stem cells will prove more effective remains to be seen.