الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
Numerous reports have suggested that multipotential cells of the BM give rise to hepatocytes, neurons, or primitive mesenchymal cells. These experiments report an unexpected plasticity or transdetermination of multipotent stem cells (or their progeny) when located in ectopic environments.
It has been suggested recently that human HSCs, particularly those isolated from cord blood, can also give rise to hepatocyte cells. Human CD34+ cord blood cells were engrafted into mice after low-dose irradiation. If such animals were then exposed to liver injury, particularly carbon tetrachloride, human cells that produce albumin, a hepatocyte marker, can be found at low frequency (< 1 of 1000). This finding suggests that human HSCs may also be able to produce hepatocytes, especially after injury. This finding has been reported independently by multiple groups.
The mechanism of hepatocyte regeneration after partial hepatectomy includes at least two ways. That is, the remaining mature hepatocytes proliferate and circulating BM stem cells migrate into residual liver and differentiate into hepatocytes. With the development and application of stem cell technique, it is possible to obtain stem cells from BM or blood and to make the stem cells proliferate in a great deal. Stem cell autotransplantation may become a new method to promote liver regeneration.
It included 24 adult male albino rats. Each rat weighed about 150-300 g at the beginning of the study. All animals received food, water and libitum and housed in spacious wire mesh cages in room maintained at constant temperature and humidity. The studied animals were divided into 4 groups; first group (control group) included 6 normal rats. Second group (PH group) included 6 rats in which 70% PH was done. Third group (Benzene group) included 6 rats of in which bone marrow (BM) suppression was carried out by Benzene injection. Ten injections were performed subcutaneously in a period of 3 weeks for induction of BM suppression. Fourth group (Benzene + PH group) included 6 rats in which BM suppression was carried out as 3rd group. Seventy percent PH was then done to them as in the second group.
Our results found that the values of restored number of hepatocytes(both centrilobular&peripheral) by the seventh day in the PH and the Benzene + PH groups were much lower than the values of hepatocytes(both centrilobular&peripheral) in the control group. The differences between control and PH groups, and PH and Benzene + PH groups of rats, are all statistically significant (P < 0.01). This finding is reflected that, after partial hepatectomy, the liver begin to restore its capacity of hepatocytes but still not restoring its full number of hepatocytes as shown by lower hepatocytes values in the PH group. The values of restored hepatocytes(both centrilobular&peripheral) in the Benzene + PH group was significantly lower than that of the PH group, which indicated that the Benzene do its role in suppressing the production of HSCs by the BM. This finding may prove the participation of the HSCs in repopulation of the liver hepatocytes.
In the normal control livers the binucleate cells were 69±11.5 the results have been calculated from average values for three regenerating groups at the seventh day after partial hepatectomy; 33.8±5.6, 60±12.4, 44±10.1in PH only, Benzene, and Benzene + PH groups respectively. Binucleate cells are significantly higher in normal (control group) than in regenerating livers (PH only and Benzene + PH groups).
Regarding degree of immunostaining there was significant higher CD34+ staining in PH group than the three other groups (p<0.01), while there was no significant difference between control, Benzene & PH + Benzene groups (p>0.05).
The hepatocytes can regenerate the liver and restore its original size. Hematopoietic stem cells may habitat the endothelial cells in the liver. Their role in hepatic regeneration doesn’t appear early after partial hepatectomy.