Lanjuan Li

Eighteen mouse monoclonal antibodies were selected for reactivity with cell surface antigens of the immunizing human melanoma cell line SK-MEL-28. Six distinct antigenic systems were defined by direct serological assays and absorption tests with a panel of 41 cell lines derived from normal and malignant human tissues. Biochemical analysis indicated that two of the antigens are glycoproteins with molecular sizes of 95,000 and 150,000 daltons (gp95 and gp150). Two other antigenic systems (O5 and the R24 group) are associated with heat-stable molecules having the characteristics of glycolipids. The remaining two antigens (M19 and R8) are heat labile, but molecular characterization has not been possible. Each of the antigenic systems has a distinctive pattern of distribution on various cell types, varying from a broad representation to a more restricted occurrence. O5 appears to be a species antigen, being present on virtually every human cell type tested. gp95, gp150, M19, and R8 are found on a characteristic proportion of melanomas, astrocytomas, and epithelial cancers and on normal kidney cells. The antigen defined by the R24 antibody has the most restricted distribution of all. Reactivity is found with melanomas and astrocytomas, whereas epithelial cell types, fibroblasts, and cells of hematopoietic origin lack R24. Although occurrence of gp95, gp150, M19, and R8 distinguishes a small subset of melanomas not expressing these antigens, R24 is found on all melanoma cells.

Sera from 28 patients with renal cancer were tested for reactivity with surface antigens of cultured autologous renal cancer cells. Four serological assays were used to survey sera for autologous antibody. Immune adherence, protein A, and C3-mixed hemadsorption assays detected reactivity in a high percentage of patients (80-100%), whereas mixed hemadsorption assays were negative with sera from all but one patient. Reactive sera from six patients were analyzed by absorption tests with autologous, allogeneic, and restricted to autologous renal cancer cells; class 2 antigens, present on certain allogeneic renal and nonrenal cancer cells; and class 3 antigens, found on a wide variety of normal and malignant cell types. The sera of one patient detected class 1, 2, and 3 antigens, the sera of three patients detected class 2 antigens, and the sera of two patients detected class 3 antigens. This analysis of renal cancer, with the recognition of three classes of surface antigens recognized by autologous sera, resembles the results of autologous typing of three other human malignancies: malignant melanoma, acute leukemia, and astrocytoma. Evidence provided by autologous typing of these cancers indicates that class 1 and class 2 antigens are tumor-restricted and that under certain circumstances these antigens are immunogenic for the autologous host.

AH antigen, initially defined by an antibody present in a melanoma patient, is a cell surface antigen found on approximately 65% of melanoma cell lines. Absorption analysis indicates that AH is a differentiation antigen marking normal and malignant cells of neuroectodermal origin. The AH determinant has been found to be related to GD2 ganglioside.

Various hepatoxic factors, such as viruses, drugs, lipid deposition, and autoimmune responses, induce acute or chronic liver injury, and 3.5% of all worldwide deaths result from liver cirrhosis, liver failure, or hepatocellular carcinoma. Liver transplantation is currently limited by few liver donors, expensive surgical costs, and severe immune rejection. Cell therapy, including hepatocyte transplantation and stem cell transplantation, has recently become an attractive option to reduce the overall need for liver transplantation and reduce the wait time for patients. Recent studies showed that mesenchymal stem cell (MSC) administration was a promising therapeutic approach for promoting liver regeneration and repairing liver injury by the migration of cells into liver sites, hepatogenic differentiation, immunoregulation, and paracrine mechanisms. MSCs secrete a large number of molecules into the extracellular space, and soluble proteins, free nucleic acids, lipids, and extracellular vesicles (EVs) effectively repair tissue injury in response to fluctuations in physiological states or pathological conditions. Cell-free-based therapies avoid the potential tumorigenicity, rejection of cells, emboli formation, undesired differentiation, and infection transmission of MSC transplantation. In this review, we focus on the potential mechanisms of MSC-based cell-free strategies for attenuating liver injury in various liver diseases. Secretome-mediated paracrine effects participate in the regulation of the hepatic immune microenvironment and promotion of hepatic epithelial repair. We look forward to completely reversing liver injury through an MSC-based cell-free strategy in regenerative medicine in the near future.

Chronic Liver fibrosis may progress to liver cirrhosis and hepatocellular carcinoma (HCC), hence cause a substantial global burden. However, effective therapies for blocking fibrosis are still lacking. Although mesenchymal stem cells (MSCs) have been proven beneficial to liver regeneration after damage, the underlying mechanism of their therapeutic effects are not fully understood. Oxidative stress and mitochondrial functionality alteration directly contributes to the hepatocyte apoptosis and development of liver fibrosis. This study aims to elucidate the mechanism by which hUC-MSC alleviates liver fibrosis and mitochondrial dysfunction. RNA-sequencing was performed to characterize the transcriptomic changes after implantation of hUC-MSCs in mice with liver fibrosis. Next, western blot, RT-PCR, immunohistochemical and immunofluorescence staining were used to evaluate the expression of different genes in vitro and in vivo. Additionally, mitochondrial morphological and dynamic changes, ROS content, and ATP production were examined. Slc25a47, a newly identified liver-specific mitochondrial NAD+ transporter, was notably reduced in CCl4-treated mice and H2O2-stimulated hepatocytes. Conversely, hUC-MSCs increased the Slc25a47 expression and NAD+ level within mitochondria, thereby enhanced Sirt3 protein activity and alleviated mitochondrial dysfunction in the liver. Furthermore, Slc25a47 knockdown could partially abrogate the protective effects of hUC-MSCs on H2O2-induced mitochondrial fission and oxidative stress in hepatocytes. Our study illustrates that Slc25a47 is a key molecular for hUC-MSCs to improve liver fibrosis and regulates mitochondrial function through Sirt3 for the first time, and providing a theoretical basis for the clinical translation of hUC-MSCs transplantation in the treatment of patients with liver fibrosis/cirrhosis.