Biomedical subjects

Ian Rogers

Publications and source records attributed to Ian Rogers.

5 recordsLinked to original sources

PubMed2006

Clinically relevant expansion of hematopoietic stem cells with conserved function in a single-use, closed-system bioprocess.

The clinical potential of umbilical cord blood-derived stem and progenitor cells has been demonstrated in various animal and human transplantation studies. However, the need for increased numbers of appropriate umbilical cord blood-derived cells continues to limit the development and success of these therapies. Ex vivo expansion has been widely studied as a method to overcome this limitation. We describe the use of a clinically relevant single-use, closed-system bioprocess capable of generating greater numbers of hematopoietic stem and progenitor cells that maintain in vivo and in vitro developmental potential. In addition to expanded numbers of CD34+ cells, CD34(+)CD38(-) cells, colony-forming cells, and long-term culture-initiating cells, the bioprocess generated > or =3.3-fold more long-term nonobese diabetic/severe combined immunodeficient repopulating cells (quantitatively determined using limiting dilution analysis) than present at input. Interestingly, these cells were also capable of multilineage engraftment and were shown to maintain their engraftment potency on a per long-term nonobese diabetic/severe combined immunodeficient repopulating cell basis compared with input noncultured cells. The developmental capacity of bioprocess-generated cells was further demonstrated by their ability to repopulate secondary nonobese diabetic/severe combined immunodeficient recipients. In vitro lineage analysis confirmed that bioprocess-generated cells could differentiate into myeloid and natural killer, B, and T cell lymphoid lineages. This in-depth analysis describes a bioprocess that generates human hematopoietic stem and progenitor cells with conserved hematopoietic activity, establishes analysis criteria for in vitro hematopoietic stem cell expansion studies, and serves as a foundation to test the therapeutic utility of cultured hematopoietic stem cells in large animals and humans.

Animals↗

PubMed2005

Dynamic changes in cellular and microenvironmental composition can be controlled to elicit in vitro human hematopoietic stem cell expansion.

OBJECTIVE: The absence of effective strategies for the ex vivo expansion of human hematopoietic stem cells (HSCs) limits the development of many cell-based therapies. Prior attempts to stimulate HSC expansion have focused on media supplementation using cytokines and growth factors. In these cultures, cellular and microenvironmental compositions change with time. In this study, the impact of controlling these dynamic changes on HSC output is determined. MATERIALS AND METHODS: Cord blood-derived lin(-) cells were cultured for 8 days in serum-free medium supplemented with stem cell factor, Flt3 ligand, and thrombopoietin. Functional, phenotypic, and molecular (gene and protein) analyses were used to characterize dynamic changes in cellular and microenvironmental composition. The effects of these changes and the mechanism behind their effects on HSC expansion were assessed using a selection/media exchange-based global culture manipulation (GCM) technique. RESULTS: We show that the direct secretion of negative regulators by culture-generated lin(+) cells, and the indirect stimulation of cells to secrete negative regulators by culture-conditioned media, limits in vitro HSC generation. The GCM strategy was able to abrogate these effects to produce elevated numbers of LTC-ICs (14.6-fold relative to input), migrating rapid NOD/SCID repopulating cells (12.1-fold), and long-term NOD/SCID repopulating cells (5.2-fold). CONCLUSIONS: Cellular and microenvironmental changes that occur during all in vitro HSC cultures can significantly affect HSC output through the direct or indirect secretion of negative regulators. This study provides insight into the mechanisms regulating HSC fate in vitro and describes a novel methodology to regulate overall in vitro microenvironmental dynamics to enable the generation of clinically relevant numbers of HSCs.

Animals↗

PubMed2004

Umbilical cord blood stem cells.

The umbilical cord contains a rich source of haematopoietic stem cells that can be used to reconstitute the blood system and can easily be extracted and cryopreserved, thus allowing for the establishment of HLA-typed stem cell banks. Recently, it has been demonstrated that umbilical cord stem cells have the potential to give rise to non-haematopoietic cells, such as bone, neural and endothelial cells. It is not clear whether these multipotential cells are mesenchymal-like cells or blood cells. Currently, the number of these specialized cells capable of undergoing the differentiation process into non-haematopoietic cells is low and remains a block to the clinical development of umbilical cord stem cells for non-haematopoietic cell therapy. Further research will allow us to overcome these hurdles. This expanded potential for umbilical cord stem cells might replace embryonic stem cells and other fetal cells for some cell and tissue therapies.

Adult↗

PubMedDate not supplied

Resveratrol, a natural aryl hydrocarbon receptor antagonist, protects lung from DNA damage and apoptosis caused by benzo[a]pyrene.

Benzo[a]pyrene (BaP) is an agonistic ligand for the aryl hydrocarbon receptor (AhR) and a major environmental carcinogen implicated in the aetiology of lung cancer through the induction of benzo[a]pyrene diol epoxidation (BPDE) and BPDE-DNA adducts. Because BaP metabolization requires cytochrome P-450 1A1 (CYP1A1) induction through activation of the AhR, we hypothesized that resveratrol, a natural competitive inhibitor of AhR, could prevent these adverse effects of BaP on the lung. Balb-C mice were injected for 5 weeks with corn oil, BaP (5 mg kg(-1) week(-1)), resveratrol (50 mg kg(-1) week(-1)) or BaP + resveratrol. Immunohistochemistry was performed on lung sections for the determination of CYP1A1 protein, BPDE-DNA adducts and apoptosis. A semi-quantitative immunohistochemistry score (H score) was used for data analysis. Mice exposed to BaP had a significant induction of lung BPDE-DNA adducts when compared with controls (H scores: control, 26, interquartile range 18-33; BaP, 276, interquartile range 269-288; P < 0.01). The BPDE-DNA adduct induction by BaP was abrogated significantly by resveratrol (H score: BaP + resveratrol, 103, interquartile range 96-113). A similar pattern was found by immunohistochemistry for apoptosis (H scores: control, 121, interquartile range 102-137; BaP, 288, interquartile range 282-292, P < 0.05; BaP + resveratrol, 132, interquartile range 121-141, P = NS) and CYP1A1 (H scores: control, 170.3, interquartile range 164-175; BaP, 302.3, interquartile range 291-315, P < 0.05; BaP + resveratrol, 200.7, interquartile range 174-215, P = NS). Western blotting confirmed that resveratrol prevented BaP-induced CYP1A1 expression. This increase in CYP1A1 expression in response to BaP administration most likely causes BaP metabolism, BPDE-DNA adduct formation and subsequent apoptosis. All BaP-induced effects could be prevented by resveratrol, suggesting a possible chemopreventive role for this natural phytoalexin against the development of lung cancer.

Animals↗

PubMedDate not supplied

Stem cells: you can't tell a cell by its cover.

Embryonic stem (ES) cells are capable of unlimited self-renewal and have the ability to give rise to all tissue types in the body. The use of human ES cells for tissue and cell therapeutics has been suggested, but is limited by ethical concerns as these cells are derived from the inner cell mass of human embryos. In addition, the need for HLA matching of ES cell-derived tissues for allogeneic transplantation would require a bank of several thousand ES cell lines to make tissue therapeutics practical. Recently, adult stem cells-of which those in bone marrow are the best studied-have been shown to be capable of multilineage differentiation into cells of various non-blood tissues. Umbilical cord blood (UCB) haematopoietic stem cells have been shown to be equivalent to bone marrow stem cells for reconstitution of the haematopoietic system. Preliminary studies have also demonstrated that UCB haematopoietic stem cells are multipotent and capable of differentiating into non-blood cell types. This observation raises the exciting possibility of replacing human ES cells for tissue and cell therapeutics with UCB blood haematopoietic stem cells that are normally discarded with the placenta after delivery.

Adult↗