Summary The effect of un-engineered (naïve) human umbilical cord matrix stem cells (hUCMSC) on the metastatic growth of MDA 231 xenografts in SCID mouse lung was examined. Three weekly IV injections of 5 × 105 hUCMSC significantly attenuated MDA 231 tumor growth as compared to the saline-injected control. IV injected hUCMSC were detected only within tumors or in close proximity to the tumors. This in vivo result was corroborated by multiple in vitro studies such as colony assay in soft agar and [3H]-thymidine uptake. These results suggest that naïve hUCMSC may be a useful tool for cancer cytotherapy.

Genetically engineered stem cells efficiently deliver therapeutic proteins to cancer and other sites of inflammation. However, a major advantage would be realized if tumortrafficking stem cells that have not been genetically modified exhibit an inherent antitumor effect, thus circumventing the necessity of the expression of exogenous genes by the cells. We transplanted Fisher 344 rat-derived mammary adenocarcinoma cells (Mat B III) orthotopically into syngeneic F344 rats with an intact immune system. Rat umbilical cord matrix stem (rUCMS) cells derived from Wharton's jelly were then administered intratumoral (i.t) or i.v. 4 days later. The tumor attenuation effect was significantly evident starting from day 14 in i.v. and i.t. rUCMS cell-transplanted rats compared with sham-transplanted rats. In addition, unmodified rUCMS celltransplanted rats showed complete regression of tumors to undetectable levels by 34 to 38 days with no evidence of metastasis or recurrence 100 days post-tumor cell inoculation. Dye-loaded rUCMS cells were identified within tumors only 4 days after their i.v. transplantation. In vitro colony assays with rUCMS cells as feeder layers markedly reduced Mat B III colony size and number. Growth attenuation of Mat B III cells exposed to either rUCMS cells directly or to the conditioned medium derived from rUCMS cells was associated with apoptosis indicators, including increased activated caspase-3. In addition, rUCMS cells cocultured with Mat B III cells had a dose-dependent antiproliferative effect on Mat B III cells. These findings suggest that unmodified human UCMS cells could be used for targeted cytotherapy for breast cancer.

BackgroundPancreatic cancer is one of the most aggressive human malignancies, with a very poor prognosis. To evaluate the effect of angiotensin II (Ang II) type 2 receptor (AT2) expression in the host's body on the growth of pancreatic carcinoma, we have investigated the growth of mouse pancreatic ductal carcinoma grafts in syngeneic wild type and AT2 receptor-deficient (AT2-KO) mice.MethodsThe role of AT2 receptor-signaling in stromal cells on the growth of murine pancreatic carcinoma cells (PAN02) was studied using various in vitro and in vivo assays. In vivo cell proliferation, apoptosis, and vasculature in tumors were monitored by Ki-67 immunostaining, TUNEL assay, and von Willebrand factor immunostaining, respectively. In the co-culture study, cell proliferation was measured by MTT cell viability assay. All the data were analyzed using t-test and data were treated as significant when p < 0.05.ResultsOur results show that the growth of subcutaneously transplanted syngeneic xenografts of PAN02 cells, mouse pancreatic ductal carcinoma cells derived from the C57/BL6 strain, was significantly faster in AT2-KO mice compared to control wild type mice. Immunohistochemical analysis of tumor tissue revealed significantly more Ki-67 positive cells in xenografts grown in AT2-KO mice than in wild type mice. The index of apoptosis is slightly higher in wild type mice than in AT2-KO mice as evaluated by TUNEL assay. Tumor vasculature number was significantly higher in AT2-KO mice than in wild type mice. In vitro co-culture studies revealed that the growth of PAN02 cells was significantly decreased when grown with AT2 receptor gene transfected wild type and AT2-KO mouse-derived fibroblasts. Faster tumor growth in AT2-KO mice may be associated with higher VEGF production in stromal cells.ConclusionsThese results suggest that Ang II regulates the growth of pancreatic carcinoma cells through modulating functions of host stromal cells; Moreover, Ang II AT2 receptor signaling is a negative regulator in the growth of pancreatic carcinoma cells. These findings indicate that the AT2 receptor in stromal fibroblasts is a potentially important target for chemotherapy for pancreatic cancer.

The endogenous angiotensin II (Ang II) type 2 receptor (AT2) has been shown to mediate apoptosis in cardiovascular tissues. Thus, the aim of this study was to explore the anti-cancer effect of AT2 over-expression on lung adenocarcinoma cells in vitro using adenoviral (Ad), FuGENE, and nanoparticle vectors. All three gene transfection methods efficiently transfected AT2 cDNA into lung cancer cells but caused minimal gene transfection in normal lung epithelial cells. Ad-AT2 significantly attenuated multiple human lung cancer cell growth (A549 and H358) as compared to the control viral vector, Ad-LacZ, when cell viability was examined by direct cell count. Examination of annexin V by flow cytometry revealed the activation of the apoptotic pathway via AT2 over-expression. Western Blot analysis confirmed the activation of caspase-3. Similarly, poly (lactide-co-glycolic acid) (PLGA) biodegradable nanoparticles encapsulated AT2 plasmid DNA were shown to be effectively taken up into the lung cancer cell. Nanoparticle-based AT2 gene transfection markedly increased AT2 expression and resultant cell death in A549 cells. These results indicate that AT2 over-expression effectively attenuates growth of lung adenocarcinoma cells through intrinsic apoptosis. Our results also suggest that PLGA nanoparticles can be used as an efficient gene delivery vector for lung adenocarcinoma targeted therapy.

Umbilical cord matrix stem (UCMS) cells that were engineered to express interferon-beta (IFN-beta) were transplanted weekly for three weeks into MDA 231 breast cancer xenografts bearing SCID mice in combination with 5-fluorouracil (5-FU). The UCMS cells were found within lung tumors but not in other tissues. Although both treatments significantly reduced MDA 231 tumor area in the SCID mouse lungs, the combined treatment resulted in a greater reduction in tumor area than by either treatment used alone. These results indicate that a combination treatment of UCMS-IFN-beta cells and 5-FU is a potentially effective therapeutic procedure for breast cancer.