To date, PCs isolated from both rat and human pancreas and human kidney have been shown to completely reverse diabetes induced in a mouse with the chemical STZ. In addition, rat pancreas-derived PCs have been effective in animal models of renal reperfusion injury and myocardial infarction.
PCs have shown efficacy in three different animal models of diabetes, cardiac ischemia, and renal reperfusion injury. These models have tested PCs from both rat and human sources. The PCs have been isolated from both the pancreas and the kidney. In each of these models, the PCs have been administered intravenously.
|Species||Tissue Source||Target Organ|
Mice were made diabetic by administering high doses of the chemical STZ. This destroys the insulin producing cells in the pancreas and induces severe diabetes characterized by markedly increased blood glucose levels, weight loss, and ultimately death. PCs were administered as an intravenous injection twenty-four hours after the STZ, and again, seven days later.
As can be seen in the above graph, animals that received PCs, from either rat or human sources, showed a significant and long-lasting reduction in their blood glucose levels. These reached normal levels approximately forty days after treatment, and were maintained at that level throughout the remainder of the study (total of ninety days).
A collaboration was established with the laboratory of Dr. B. Metzler of the Division of Cardiology, Department of Internal Medicine, University Hospital of Innsbruck. This laboratory has an established model of cardiac infarct injury (Metzler, B. et al., Clinica Chimica Acta 325, 87-90, 2002), in which the left descending artery is ligatured during a surgical procedure, preventing blood supply to the left ventricle in particular.
The extent of the infarct damage is assessed by plasma cardiac troponin measurement, which was measured weekly. Cardiac function is determined before termination of the experiment at days 7 and 14 after ischemia, by in vivo determination using ultrasound of systolic left ventricle size (smaller corresponds to better function – i.e. less muscle damage), and fractional shortening (the ratio of heart size when full with blood to heart size after emptying, which reflects how much the heart muscle needs to contract to eject a normal volume of blood), where increased fractional shortening corresponds to increased heart function (normal is 50%).
As seen in the following graph, there was a significant difference between controls and treated animals (pink line).
In addition to fractional shortening, which is a measure of heart function, cardiac tissue was analyzed for markers of cell damage.
The marker p21 was measured in tissue taken from two areas of the heart. Animals with ischemia and no treatment (red) showed an increased level, which was made worse in animals receiving sodium chloride (tan). PC treated animals (dark brown) had levels which were essentially the same as animals without any ischemia (pink).
A collaboration was established with Dr. C. Koppelstaetter and colleagues of the Clinical Division of Nephrology, Innsbruck Medical University. This laboratory has an established model of renal ischemic reperfusion injury (Hochegger, K. et al., Am. J. Physiol. Renal Physiol. 292, 762-768, 2007). This is a well-accepted model with direct relevance to acute renal failure and decreased allograft survival in the context of kidney transplantation.
Kidney function is assessed in animals after the ischemic event by determination of serum creatinine levels and urinary protein to creatinine ratio (UPCR), with increased levels corresponding to the extent of tissue damage. As in the cardiac ischemia experiments, in addition to functional measurements, tissue analysis is done based on biological markers, which correspond to damage and senescence.
There were four groups of animals: group A had ischemia but no treatment; group B received two doses of PCs seven days apart, with the first dose given twenty-four hours after ischemia; group received two doses of PCs seven days apart, but with treatment immediately after the ischemia was induced; and group D received a single dose, but with twice as many cells.
There was a significant improvement in serum creatinine levels in all treatment groups.
Tissue analysis for both cell senescence markers p21 and for SA-beta-gal also demonstrated a significant difference between treated animals and controls:
The results from these animal models demonstrate that PCs from different species and from different organs have the ability to stimulate repair of a variety of damaged organs, and suggest, at least with respect to acute injury, that this may be a universal property of the PCs.