Jong In Lee

The role of growth factors in maintenance of stemness in bone marrow-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are an active topic of research in regenerative medicine due to their ability to secrete a variety of growth factors and cytokines that promote healing of damaged tissues and organs. In addition, these secreted growth factors and cytokines have been shown to exert an autocrine effect by regulating MSC proliferation and differentiation. We found that expression of EGF, FGF-4 and HGF were down-regulated during serial passage of bone marrow-derived mesenchymal stem cells (BMSCs). Proliferation and differentiation potentials of BMSCs treated with these growth factors for 2 months were evaluated and compared to BMSCs treated with FGF-2, which increased proliferation of BMSCs. FGF-2 and -4 increased proliferation potentials at high levels, about 76- and 26-fold, respectively, for 2 months, while EGF and HGF increased proliferation of BMSCs by less than 2.8-fold. Interestingly, differentiation potential, especially adipogenesis, was maintained only by HGF treatment. Treatment with FGF-2 rapidly induced activation of AKT and later induced ERK activation. The basal level of phosphorylated ERK increased during serial passage of BMSCs treated with FGF-2. The expression of LC3-II, an autophagy marker, was gradually increased and the population of senescent cells was increased dramatically at passage 7 in non-treated controls. But FGF-2 and FGF-4 suppressed LC3-II expression and down-regulated senescent cells during long-term (i.e. 2month) cultures. Taken together, depletion of growth factors during serial passage could induce autophagy, senescence and down-regulation of stemness (proliferation via FGF-2/-4 and differentiation via HGF) through suppression of AKT and ERK signaling.

Mesenchymal Stem Cell-Mediated Effects of Tumor Support or Suppression

Mesenchymal stem cells (MSCs) can exhibit a marked tropism towards site of tumors. Many studies have reported that tumor progression and metastasis increase by MSCs. In contrast, other studies have shown that MSCs suppress growth of tumors. MSCs contribute to tumor growth promotion by several mechanisms: (1) transition to tumor-associated fibroblasts; (2) suppression of immune response; (3) promotion of angiogenesis; (4) stimulation of epithelial-mesenchymal transition (EMT); (5) contribution to the tumor microenvironment; (6) inhibition of tumor cell apoptosis; and (7) promotion of tumor metastasis. In contrast to the tumor-promoting properties, MSCs inhibit tumor growth by increasing inflammatory infiltration, inhibiting angiogenesis, suppressing Wnt signaling and AKT signaling, and inducing cell cycle arrest and apoptosis. In this review, we will discuss potential mechanisms by which MSC mediates tumor support or suppression and then the possible tumor-specific therapeutic strategies using MSCs as delivery vehicles, based on their homing potential to tumors.

Effective myotube formation in human adipose tissue-derived stem cells expressing dystrophin and myosin heavy chain by cellular fusion with mouse C2C12 myoblasts.

Stem cell therapy for muscular dystrophies requires stem cells that are able to participate in the formation of new muscle fibers. However, the differentiation steps that are the most critical for this process are not clear. We investigated the myogenic phases of human adipose tissue-derived stem cells (hASCs) step by step and the capability of myotube formation according to the differentiation phase by cellular fusion with mouse myoblast C2C12 cells. In hASCs treated with 5-azacytidine and fibroblast growth factor-2 (FGF-2) for 1 day, the early differentiation step to express MyoD and myogenin was induced by FGF-2 treatment for 6 days. Dystrophin and myosin heavy chain (MyHC) expression was induced by hASC conditioned medium in the late differentiation step. Myotubes were observed only in hASCs undergoing the late differentiation step by cellular fusion with C2C12 cells. In contrast, hASCs that were normal or in the early stage were not involved in myotube formation. Our results indicate that stem cells expressing dystrophin and MyHC are more suitable for myotube formation by co-culture with myoblasts than normal or early differentiated stem cells expressing MyoD and myogenin.

Rapid Isolation of Adipose Tissue-Derived Stem Cells by the Storage of Lipoaspirates

Purpose This study examined a rapid isolation method decreasing the time and cost of the clinical application of adipose tissue-derived stem cells (ASCs). Materials and Methods Aliquots (10 g) of the lipoaspirates were stored at 4℃ without supplying oxygen or nutrients. At the indicated time points, the yield of mononuclear cells was evaluated and the stem cell population was counted by colony forming unit-fibroblast assays. Cell surface markers, stem cell-related transcription factors, and differentiation potentials of ASCs were analyzed. Results When the lipoaspirates were stored at 4℃, the total yield of mononuclear cells decreased, but the stem cell population was enriched. These ASCs expressed CD44, CD73, CD90, CD105, and HLA-ABC but not CD14, CD31, CD34, CD45, CD117, CD133, and HLA-DR. The number of ASCs increased 1×1014 fold for 120 days. ASCs differentiated into osteoblasts, adipocytes, muscle cells, or neuronal cells. Conclusion ASCs isolated from lipoaspirates and stored for 24 hours at 4℃ have similar properties to ASCs isolated from fresh lipoaspirates. Our results suggest that ASCs can be isolated with high frequency by optimal storage at 4℃ for 24 hours, and those ASCs are highly proliferative and multipotent, similar to ASCs isolated from fresh lipoaspirates. These ASCs can be useful for clinical application because they are time- and cost-efficient, and these cells maintain their stemness for a long time, like ASCs isolated from fresh lipoaspirates.

l-Ascorbic acid 2-phosphate and fibroblast growth factor-2 treatment maintains differentiation potential in bone marrow-derived mesenchymal stem cells through expression of hepatocyte growth factor

Abstract l-ascorbic acid 2-phosphate (Asc-2P) acts as an antioxidant and a stimulator of hepatocyte growth factor (HGF) production. Previously, we reported that depletion of growth factors such as fibroblast growth factor (FGF)-2, epidermal growth factor (EGF), FGF-4 and HGF during serial passage could induce autophagy, senescence and down-regulation of stemness (proliferation via FGF-2/-4 and differentiation via HGF). In this study, we investigated the proliferation and differentiation potential of BMSCs by FGF-2 and Asc-2P. Co-treatment with FGF-2 and Asc-2P induced optimal proliferation of BMSCs and increased the accumulation rate of BMSC numbers during a 2-month culture period. Moreover, differentiation potential was maintained by co-treatment with FGF-2 and Asc-2P via HGF expression. Adipogenic differentiation potential by FGF-2 and Asc-2P was dramatically suppressed by c-Met inhibitors (SU11274). These data suggest that co-treatment with FGF-2 and Asc-2P would be beneficial in obtaining BMSCs that possess “stemness” during long-term culture.

Unusual isolated extramedullary relapse of acute lymphoblastic leukemia in the breast despite complete donor hematopoietic chimerism after allogeneic hematopoietic stem cell transplantation

pISSN 1226-3303 eISSN 2005-6648 http://www.kjim.org Copyright

973PPRETREATMENT LYMPHOPENIA AND POOR PERFORMANCE STATUS ARE RISK FACTORS OF SEVERE BACTERIAL INFECTION IN PATIENTS WITH MULTIPLE MYELOMA DURING CHEMOTHERAPY WITH BORTEZOMIB-CONTAINING REGIMENS

ABSTRACT Aim: Infection is the leading cause of morbidity and mortality in patients with multiple myeloma. The aim of this study is to identify the risk factors associated with the development of severe infections in patients with multiple myeloma during chemotherapy with bortezomib-containing regimens. Methods: A total of 98 patients with myeloma who were treated with bortezomib-based chemotherapy between 2006 and 2012 were examined. Using the logistic regression method, a variety of factors were analyzed for the development of severe bacterial infections (SBI) at each of 427 courses. Results: Median age of patients was 62 years, and 40.6% (30/98) of patients were treated with bortezomib-containing chemotherapy as first-line treatment. The SBI was developed in 57% (56/98) of patients and 19% (81/427) of bortezomib courses. Of 81 SBI episodes, 42 (53%) episodes were clinically documented infection, 30 (37%) episodes were microbiologically documented infections, and 9 (11%) episodes were fever of unknown origin. Multivariate logistic regression analysis revealed poor performance status (ECOG ≥2) (HR 3.920, 95% C.I. 2.305-6.666, P Conclusions: Patients with these risk factors (early courses of therapy, poor performance status and lymphopenia) should be more closely monitored for bacterial infections and a consideration of prophylactic use of antibiotics at least for the initial 2 courses of therapy would be helpful to decrease bacterial infections. Disclosure: All authors have declared no conflicts of interest.