Differentiation of mesenchymal cells derived from human amniotic membranes into hepatocyte-like cells in vitro.

Mesenchymal stem cells are believed to be involved in the formation of mesenchymal tissues, including bone, cartilage, muscle, tendon and adipose tissue. Interestingly, it has previously been reported that mesenchymal stem cells could also differentiate into endoderm-derived cells, such as hepatocytes. The amniotic membrane contains mesenchymal cells and is a readily available human tissue. Therefore, we investigated the potential of mesenchymal cells derived from human amniotic membrane (MC-HAM) to differentiate into hepatocytes. We analyzed the expression of hepatocyte-specific genes in MC-HAM before and after induction of differentiation into hepatocytes. We observed the expression of mRNAs encoding albumin, a-fetoprotein, cytokeratin 18 and alpha1-antitrypsin, but not those encoding glucose-6-phosphatase or ornithine transcarbamylase, prior to the induction of differentiation. However, immunocytochemistry revealed that albumin and alpha-fetoprotein were abundantly produced only after the induction of differentiation into hepatocytes. In addition, we observed the storage of glycogen, a characteristic feature of hepatocytes, using periodic acid-Schiff staining of MC-HAM induced to differentiate into hepatocytes. Overall, MC-HAM appear to be able to differentiate into cells possessing some characteristics of hepatocytes. Although further studies should be carried out to determine whether such in vitro-differentiated cells can function in vivo as hepatocytes. These cells may be useful in various applications that require human hepatocytes.

Gastric carcinoma resembling submucosal tumor.

Acase of stomach carcinoma showing features of submucosal tumor is reported. The patient was a 50-year-old man presenting with hematemesis. Endoscopic examination was performed and revealed a submucosal tumor-like lesion with central ulceration in the fornix of the stomach. The biopsy specimen from this lesion showed poorly differentiated adenocarcinoma, and surgery was performed. The tumor, measuring 3.5 x 2.7 cm in size, invaded to the muscularis propria with proliferation of the interstitial connective tissue and lymphoid follicles consisting mainly of B lymphocytes in the submucosal layer. In situ hybridization of tumor tissue for Epstein-Barr virus (EBV)-encoded small RNA1 as target revealed negative results. In stomach carcinoma simulating submucosal tumor, as in this patient, preoperative diagnosis is important to plan treatment strategies.