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Biomedical subjects

G K Naughton

Publications and source records attributed to G K Naughton.

At least 19 recordsLinked to original sources
PubMed2001

Scaffold-based three-dimensional human fibroblast culture provides a structural matrix that supports angiogenesis in infarcted heart tissue.

BACKGROUND: We have developed techniques to implant angiogenic patches onto the epicardium over regions of infarcted cardiac tissue to stimulate revascularization of the damaged tissue. These experiments used a scaffold-based 3D human dermal fibroblast culture (3DFC) as an epicardial patch. The 3DFC contains viable cells that secrete angiogenic growth factors and has previously been shown to stimulate angiogenic activity. The hypothesis tested was that a viable 3DFC cardiac patch would stimulate an angiogenic response within an area of infarcted cardiac tissue. METHODS AND RESULTS: A coronary occlusion of a branch of the left anterior descending coronary artery was performed by thermal ligation in severe combined immunodeficient mice. 3DFCs with or without viable cells were sized to the damaged area, implanted in replicate mice onto the epicardium at the site of tissue injury, and compared with animals that received infarct surgery but no implant. Fourteen and 30 days after surgery, hearts were exposed and photographed, and tissue samples were prepared for histology and cytochemistry. Fourteen and 30 days after surgery, the damaged myocardium receiving viable 3DFC exhibited a significantly greater angiogenic response (including arterioles, venules, and capillaries) than nonviable and untreated control groups. CONCLUSIONS: In this animal model, viable 3DFC stimulates angiogenesis within a region of cardiac infarction and can augment a repair response in damaged tissue. Therefore, a potential use for 3DFC is the repair of myocardial tissue damaged by infarction.

Animals↗
PubMed1999

Human-based tissue-engineered implants for plastic and reconstructive surgery.

The emerging field of tissue engineering focuses on the creation of living tissues and organs for use in tissue repair and transplantation. Human cells are seeded onto biocompatible scaffolds and grown under physiologic conditions to produce all-human biointeractive implants. Tissue-engineered skin implants have shown efficacy in a variety of wound applications. Near term products, including injectable human matrix for contour defects and tissue-engineered cartilage, are proving to be important tools for plastic and reconstructive surgery.

Biotechnology↗
PubMed1991

In vitro toxicity of various classes of test agents using the neutral red assay on a human three-dimensional physiologic skin model.

A new three-dimensional human skin model consisting of several layers of actively dividing and metabolically active human neonatal foreskin-derived fibroblasts and epidermal keratinocytes grown on nylon mesh has been used to assess the in vitro toxicity of test agents from various classes. Utilizing a slight modification of the published neutral red viability assay for endpoint determination, we have assayed and obtained dose-dependent toxicity curves for test agents from the following classes: detergents (n = 15), alcohols (n = 5), metal chlorides (n = 10), perfumes and colognes (n = 5), shampoos (n = 4), conditioners (n = 3), moisturizers (n = 3), pesticides (n = 3), and antimicrobial preservatives (n = 4). Limited comparisons to in vivo ocular irritancy data with alcohols and detergents are encouraging. We have demonstrated the utility of this metabolically active dermal substrate containing naturally secreted collagen and other extracellular matrix proteins along with the neutral red viability assay for assessing the toxicity of a number of test agents from a variety of different classes with broad industrial applications.

Alcohols↗
PubMed1991

Hematopoiesis on suspended nylon screen-stromal cell microenvironments.

A three-dimensional culture system for the growth of primate and rodent bone marrow was developed in our laboratory. This method involves the seeding of stromal cells onto a nylon screen and the inoculation of fresh or cryopreserved bone marrow hematopoietic cells after stromal cell processes had extended across 3 to 4 out of every 5 mesh openings. Stromal cells attach, grow, and secrete matrix proteins which contribute to an intricate microenvironment for the support of multilineage hematopoiesis, which was observed for greater than 270 days in the rat model and for greater than 12 weeks in the human system, as evidenced by flow cytometry analysis and in vitro clonogenic assays. The adherent zones of these suspended nylon screen cultures consisted primarily of immature cells. These cultures could also be used as substrates for cytotoxicity measurements; treatment of rat bone marrow cultures of various ages with cytosine beta-D arabinofuranoside, cyclophosphamide, 5-fluorouracil, or methotrexate resulted in a dose-dependent decrease in CFU-C numbers and altered the phenotypic distribution of hematologic cells in the adherent zone. The use of a modification of this method to generate large numbers of active cytolytic cells after greater than 75 days culture of rat bone marrow-derived natural killer cells is described also. Suspended nylon screen bone marrow culture also has potential uses in genetic insertion and graft vs. host disease studies, blood component therapy, the evaluation of ex vivo purging programs, and in marrow expansion for transplantation.

Animals↗
PubMed1990

A three-dimensional culture system for the growth of hematopoietic cells.

A physiological three-dimensional culture system was developed for the growth of human bone marrow. Bone marrow stromal cells were established on a nylon filtration screen template, suspended in liquid medium and grown to 70% confluence, and inoculated with hematopoietic cells. An intricate microenvironment is established to support hematopoiesis, which proceeds in a three-dimensional orientation. Analysis of the adherent zone of these cultures with flow cytometry and progenitor cell assays reveals multilineage hematologic expression and active proliferation of immature cells for the 12 week experimental period. Similar results were obtained with rat bone marrow cultures using this methodology. The suspended nylon mesh system is novel in that it supports the growth of several hematologic lineages concurrently. This system may lend itself to the growth of purged or untreated bone marrow for transplantation.

Animals↗
PubMed1987

Hematopoiesis on nylon mesh templates. I. Long-term culture of rat bone marrow cells.

Rodent hematopoietic cells have been perpetuated in long-term bone marrow culture (LTBMC), provided that they were plated onto a pre-established layer of bone marrow stromal cells (fibroblasts, reticular cells, adipocytes, macrophages, etc.). This monolayer-type system supports the self-renewal of murine pluripotent stem cells and produces substantial numbers of progenitors and mature cells of the myeloid lineage. In an effort to increase the growth potential of cells in LTBMC, an adherent matrix of stromal cells was established on a pretreated nylon screen template. Subsequent seeding of hematopoietic cells onto this matrix occurred both on the surface of the adherent layer and in the interstices formed by the developing stromal cells. A three dimensional growth pattern of hematopoietic colonies and clusters was observed. Mature cells and late stage precursors of the myeloid and erythroid series were observed in the non-adherent layer for the duration of the experiment (39 weeks). Cells similar in appearance to small lymphocytes were also seen in both the non-adherent and adherent layers. Cells associated with the adherent layer of this LTBMC system displayed the ability to reconstitute hematopoiesis in the irradiated host. It is suggested that because of its three-dimensional nature the nylon mesh LTBMC system possesses a greater hematologic potential per unit area than monolayer-type LTBMC.

Animals↗
PubMed1986

Correlation between vitiligo antibodies and extent of depigmentation in vitiligo.

We correlated the level of vitiligo antibodies to the extent of depigmentation in thirty-two patients with vitiligo. Vitiligo antibodies were assayed by protein A-sepharose immunoprecipitation method. Antibodies were present in four of eight (50%) patients with minimal vitiligo (less than 2% body surface involved), in nine of ten (90%) patients with moderate vitiligo (2 to 5% surface involved), and in thirteen of fourteen (93%) patients with more extensive disease (greater than 5% surface involved). The level of vitiligo antibodies in the three groups expressed as a binding index was 2.9% +/- 2.03, 5.6% +/- 2.92, and 8.0% +/- 3.03 SD, respectively. These results suggest that there is a relation between the incidence and level of vitiligo antibodies and the extent of depigmentation in vitiligo.

Adult↗
PubMed1986

Antibodies to surface antigens of pigmented cells in animals with vitiligo.

All of 24 animals (dogs, cats, and horses) with vitiligo were found to have antibodies to pigmented cells that could be detected by specific immunoprecipitation of radioiodinated, detergent-soluble surface macromolecules, and by indirect immunofluorescence on viable cells. These antibodies were not detected in 17 normal animals of the same species. The antibodies were directed to an 85-kDa surface antigen selectively expressed by pigmented cells that was not present on nonpigmented control cells. These observations suggest that vitiligo in animals is an autoimmune disease mediated to pigmented cells.

Animals↗
PubMed1985

Erythropoietin production by macrophages in the regenerating liver.

The site of erythropoietin (Ep) production and/or storage in the rat liver was determined. A guinea pig anti-Ep was produced against purified rat Ep (64,096 +/- 4j064 IU/mg). This antibody was found to be highly specific using rocket immunoelectrophoresis, Ouchterlony gel diffusion methods, and immunoprecipitin reactions as well as Ep neutralization tests (capable of completely neutralizing up to 2,000 IU Ep/mg). This anti-Ep was labeled with either fluorescein for light microscopic study or ferritin for electron microscopy. Kupffer cells showed varying degrees of labeling after hepatectomy alone or hepatectomy combined with nephrectomy and/or hypoxia. Greatest labeling was seen in Kupffer cells of rats that were nephrectomized 48 hr posthepatectomy and kept at ambient pressure. No labeling of hepatocytes or vascular and bile duct endothelium was noted.

Animals↗
PubMed1985

Vitiligo-related pigment cell differentiation antigens are expressed on malignant melanoma cells following phenotypic reversion induced by contact inhibitory factor.

Most vitiligo sera contain antibodies to surface antigens on pigmented human melanocytes but not to human or mouse amelanotic melanoma cells. A density-dependent line of hamster amelanotic melanocytic cells (FF) produces a diffusible factor (CIF) which restores contact inhibition of growth as well as several other normal phenotypic characteristics to hamster, murine, and human melanoma cells. The ability of CIF to induce the expression of a phenotypic characteristic of pigmented human melanocytic cells, i.e., the vitiligo-related surface antigens, on hamster and mouse amelanotic melanoma cells was investigated. Vitiligo and normal sera were reacted with CIF-treated and untreated hamster and mouse amelanotic melanoma cells for both indirect-immunofluorescence assays and ELISA. Immunofluorescence testing showed that about 80% of hamster and mouse melanoma cells had pigment-cell antigens (in the absence of pigmentation) in a granular surface pattern after, but not prior to, CIF-induced morphologic reversion and confluent growth. Less than 5% of the control hamster and mouse melanoma cells expressed such antigens at confluence. These results were confirmed by ELISA. Metabolic-labeling studies with 35S-methionine showed that the vitiligo antigens were synthesized by the CIF-treated melanoma cells. The slowing of melanoma cell proliferation in isoleucine-deficient medium failed to elicit the expression of vitiligo antigens. Since antigen appearance following phenotypic reversion occurred without pigment induction, it is concluded that vitiligo-related surface antigens and pigmentation are distinct aspects of a differentiated function which may be non-coordinately expressed. The expression of pigment-cell differentiation antigens on amelanotic melanoma cells is an additional feature of the pleiotypic trans-species response to CIF.

Animals↗
PubMed1984

Expression of vitiligo antigen on a revertant line of hamster melanoma cells.

Our laboratory has recently reported that over 80% of patients with common vitiligo have circulating antibodies to cell-surface antigens on normal human melanocytes. The slow growth rate of these cells limits the assays that can be performed for antibody detection. We now have found that the antigens defined by vitiligo sera on melanocytes are also expressed on FF cells, a revertant line of hamster melanoma cells. These antigens can be detected both by indirect immunofluorescence and specific immunoprecipitation assays. The presence of "vitiligo" antigens on hamster FF cells will aid further study of the abnormal immune response in vitiligo.

Animals↗
PubMed1983

Antibodies to normal human melanocytes in vitiligo.

Most patients with active vitiligo (82% of 61) have antibodies to antigens of normal human melanocytes that can be detected by specific immunoprecipitation of radioiodinated, detergent-soluble, melanocyte macromolecules. Such antibodies were present in only 12% of patients with melanoma and in none of 35 patients with nonpigmentary skin diseases. The antibodies were directed to a common antigen(s) on melanocytes that was not present on normal fibroblasts or keratinocytes. These observations suggest that vitiligo is an autoimmune disease mediated by antibodies to melanocyte-associated antigen(s).

Antibodies↗
PubMed1983

Detection of antibodies to melanocytes in vitiligo by specific immunoprecipitation.

Immunoprecipitation was used to assay for antibodies to normal human melanocytes in the sera of 12 patients with common vitiligo and 12 normal individuals. The procedure is based on the specific immunoprecipitation using protein A-sepharose of antibodies binding to detergent-soluble, radioiodinated macromolecules of normal human melanocytes grown in culture. Antibodies to melanocytes were found in all 12 patients with vitiligo but in none of the normal sera. None of the sera reacted specifically to normal human fibroblasts or to human melanoma cells radioiodinated in a similar manner. These observations suggest that antibodies to melanocyte-associated antigens are present in common vitiligo.

Antibody Specificity↗