STEM CELLS 2006;24:74 -85

Mesenchymal stem cells (MSCs) are multipotent cells defined by multilineage potential, ease to gene modification, and immunosuppressive ability, thus holding promise for tissue engineering, gene therapy, and immunotherapy. They exhibit a unique in vitro expansion capacity, which, however, does not compensate for the very low percentage in their niches given the vast numbers of cells required for the relative studies. Taking into consideration the lack of a uniform approach for MSC isolation and expansion, we attempted in this study, by comparing various culture conditions, to identify the optimal protocol for the large-scale production of MSCs while maintaining their multilineage and immunosuppressive capacities. Our data indicate that, apart from the quality of fetal calf serum, other culture parameters, including basal medium, glucose concentration, stable glutamine, bone marrow mononuclear cell plating density, MSC passaging density, and plastic surface quality, affect the final outcome. Furthermore, the use of basic fibroblast growth factor (bFGF), the most common growth supplement in MSC culture media, greatly increases the proliferation rate but also upregulates HLA-class I and induces low HLA-DR expression. However, not only does this upregulation not elicit significant in vitro allogeneic T cell responses, but also bFGF-cultured MSCs exhibit enhanced in vivo immunosuppressive potential. Besides, addition of bFGF affects MSC multilineage differentiation capacity, favoring differentiation toward the osteogenic lineage and limiting neurogenic potential. In conclusion, in this report we define the optimal culture conditions for the successful isolation and expansion of human MSCs in high numbers for subsequent cellular therapeutic approaches.

The aim of the study was to investigate whether a combination of mesenchymal stem cells (MSCs) capable of differentiating into cardiac myocytes and endothelial progenitors (EPCs) that mainly promote neoangiogenesis might be able to facilitate tissue repair in myocardial scars. Previous studies have shown that intracoronary transplantation of autologous bone marrow stem cells results in improvement of contractility in infracted areas of human myocardium. Eleven patients with an anteroseptal myocardial infarction (MI) underwent transcoronary transplantation of bone marrow-derived MSCs and EPCs to the infarcted area through the left anterior descending artery. Eleven age- and sex-matched patients served as controls. Wall motion score index was significantly lower at follow-up in the transplantation (P = 0.04) but not in the control group. On stress echocardiography, there was improvement of myocardial contractility in one or more previously nonviable myocardial segments in 5 out of 11 patients (all with recent infarctions) and in none of the controls (P = 0.01). Restoration of uptake of Tc(99m) sestamibi in one or more previously nonviable myocardial scars was seen in 6 out of 11 patients subjected to transplantation and in none of the controls (P = 0.02). Cell transplantation was an independent predictor of improvement of nonviable tissue. Intracoronary transplantation of MSCs and EPCs is feasible, safe, and may contribute to regional regeneration of myocardial tissue early or late following MI.

HLA-mismatched natural killer (NK) cells have shown efficacy in acute myeloid leukemia, and their adoptive transfer in patients with other malignancies has been proven safe. This phase I clinical trial was designed to evaluate safety (primary endpoint) and possible clinical efficacy (secondary endpoint) of repetitive administrations of allogeneic, in vitro activated and expanded NK cells along with chemotherapy in patients with advanced non-small cell lung cancer (NSCLC). Patients with unresectable, locally advanced/metastatic NSCLC receiving 1st/2nd line chemotherapy were eligible to receive 2-4 doses of activated NK cells from two relative donors. Donor's CD56(+) cells were cultured for 20-23 days with interleukin-15 (IL-15) and hydrocortisone (HC) and administered intravenously between chemotherapy cycles. Premedication with corticosteroids and/or H1 inhibitors was allowed. Sixteen patients (performance status 0-1) with adenocarcinoma (n = 13) or squamous cell carcinoma (n = 3) at stage IIIb (n = 5) or IV (n = 11) receiving 1st (n = 13) or 2nd (n = 3) line treatment were enrolled. Fifteen patients received 2-4 doses of allogeneic activated NK cells (0.2-29 × 10(6)/kg/dose, median 4.15 × 10(6)/kg/dose). No side effects (local or systemic) were observed. At a median 22-month follow-up (range, 16.5-26 months) 2 patients with partial response and 6 patients with disease stabilization were recorded. Median progression free survival and overall survival were 5.5 and 15 months, respectively. A 56% 1-year survival and a 19% 2-year survival were recorded. In conclusion, repetitive infusions of allogeneic, in vitro activated and expanded with IL-15/HC NK cells, in combination with chemotherapy are safe and potentially clinically effective.

Mesenchymal stem cells (MSCs) are a very important adult stem cell population with a multitude of potential applications in regenerative medicine. The thorough characterization of the bone marrow MSC (BM-MSC) population derived from the BALB/c species was essential, considering the significance of the murine model amongst animal models. In the present study, we examined the effect of gender, age, and in vitro culture on the basic properties (proliferation, differentiation, and immunosuppressive potential) of BM-MSCs. We found a decline in the progenitor frequencies from the BM of adult mice, lower MSC frequencies in all female donors, and an increase in the BM-MSC proliferation rate upon in vitro propagation. We also examined BM-MSCs for the expression of the 3 major embryonic stem cell transcription factors, Oct3/4, Sox-2, and Nanog, as well as 2 mRNA binding proteins, coding region determinant binding protein/insulin-like growth factor 2 mRNA binding protein 1 (Crd-bp/Imp1) and Deleted in azoospermia-like (Dazl), which are expressed in primitive stem cells, umbilical cord blood-hematopoietic stem cells and amniotic fluid stem cells, respectively. Further, it has been reported that these 2 genes are critical for embryonic development. In this study, therefore, we report, for the first time, the expression of Crd-bp/Imp1 and Dazl in BM-MSCs. Dazl, Oct3/4, and Sox2 were detected in relatively low levels in contrast to Crd-bp/Imp1, its major target c-Myc, as well as Nanog, which were expressed redundantly, irrespective of sex, donor age, or in vitro passaging. These findings could further support the extrinsic theory of aging of the MSC population and the potential implication of embryonic genes in adult stem cell physiology.