Biomedical subjects

Charles J Roberge

Publications and source records attributed to Charles J Roberge.

6 recordsLinked to original sources

PubMed2006

Adventitia contribution in vascular tone: insights from adventitia-derived cells in a tissue-engineered human blood vessel.

Whether the adventitia component of blood vessels directly participates in the regulation of vascular tone remains to be demonstrated. We have recently developed a human tissue-engineered blood vessel comprising the three tunicae of a native blood vessel using the self-assembly approach. To investigate the role of the adventitia in the modulation of vascular tone, this tissue-engineering method was used to produce three vascular constructs from cells explanted and proliferated from donor vessel tunicae 1) an adventitia + a media, or only 2) an adventitia, or 3) a media. The vasoconstriction responses of these 3 constructs to endothelin, the most potent vasopressor known up-to-date, as well as to nonselective and selective agonists and antagonists, were compared. The adventitia contracted to endothelin-1, -2, whereas the media and the media+adventitia contracted to all three endothelins. Endothelin-induced contraction of the adventitia was dependent on ET(A) receptors, whereas that of the media and the adventitia+media was ET(A) and ET(B) receptor-dependent. RT-PCR studies corroborated these results. SNP induced a dose-dependent relaxation of the three tissue constructs. We also demonstrated that the endothelin-converting enzyme, responsible for the formation of the active endothelin peptides, was present and functional in the adventitia. In conclusion, this is the first direct demonstration that the adventitia has the capacity to contract and relax in response to vasoactive factors. The present study suggests that the adventitia of a blood vessel could play a greater role than expected in the modulation of blood vessel tone.

Aspartic Acid Endopeptidases↗

PubMed2006

Tissue-engineered human vascular media produced in vitro by the self-assembly approach present functional properties similar to those of their native blood vessels.

We have developed a tissue-engineering approach for the production of a completely biological blood vessel from cultured human cells. In the present study, we took advantage of this tissue-engineering method to demonstrate that it can be used to reproduce the subtle differences in the expression of receptors present on the media of native human blood vessels. Indeed, a small percentage (3 of 18) of native human umbilical cord veins (HUCVs) responded to endothelin, the most powerful vasopressor agent known to date, via both endothelin A (ET(A)) and endothelin B (ET(B)) receptor activation. In contrast, most HUCVs tested responded to ET via ET(A) receptor activation only. Tissue-engineered vascular media (TEVM) were next reconstructed by using vascular smooth muscle cells (VSMCs) isolated and cultured from HUCVs expressing both ET(A) and ET(B) receptors to determine the functional integrity of our TEVM model. The reconstructed TEVM presents an endothelin response similar to that of respective HUCVs from which VSMCs were isolated. Reverse transcriptase polymerase chain reaction on TEVM reconstructed in vitro correlated these vasocontractile profiles by showing the presence of messenger RNA for both ET(A) and ET(B) receptors. Taken together with recently published results on TEVM expressing only ET(A) receptor, these results show that our reconstructed TEVM present a similar ET response profile as the blood vessel from which the VSMCs were isolated and cultured. These findings indicate that subtle differences, such as receptor expression, are preserved in the reconstructed tissue. Therefore, our TEVM offers a valuable human in vitro model with which to study the functionality of human blood vessels, such as their vasoactive response, or to perform pharmacologic studies.

Blood Vessels↗

PubMed2005

Tissue-engineered human vascular media with a functional endothelin system.

BACKGROUND: Cardiovascular diseases remain a major cause of death and disability in the Western world. Among the various approaches adopted to counteract the morbidity associated with these diseases, surgical procedures and cardiac and vascular xenotransplantations or allotransplantations are routinely performed. The suitable vascular graft would be as close as possible to the native and healthy vessel composed exclusively of human components provided by the patient and would adapt to the donor's hemodynamics. We have developed such a tissue-engineered human blood vessel reconstructed with human cells. Because endothelin is the most potent vasopressor known to date, we were interested in investigating the functionality of the endothelinergic system in our reconstructed human blood vessel. METHODS AND RESULTS: Vasoconstriction studies were performed with nonselective and selective agonists and antagonists to demonstrate that ET(A) receptors were present and functional in tissue-engineered human vascular media constructed with the self-assembly method. Reverse-transcriptase polymerase chain reaction studies demonstrated that mRNA of the ET(A) but not the ET(B) receptor was present in these human tissue-engineered blood vessels. Furthermore, we demonstrated that the endothelin-converting enzyme, the main enzyme responsible for the formation of the biologically active endothelin peptides, was present and functional in these same bioengineered vascular media. CONCLUSIONS: Our results suggest that the media component of our tissue-engineered blood vessel has the potential of controlling vascular resistance via the presence of functional endothelin ET(A) receptors and endothelin-converting enzyme.

Aspartic Acid Endopeptidases↗

PubMed2005

Epidermis promotes dermal fibrosis: role in the pathogenesis of hypertrophic scars.

Hypertrophic scarring is a pathological process characterized by fibroblastic hyperproliferation and by excessive deposition of extracellular matrix components. It has been hypothesized that abnormalities in epidermal-dermal crosstalk explain this pathology. To test this hypothesis, a tissue-engineered model of self-assembled reconstructed skin was used in this study to mimic interactions between dermal and epidermal cells in normal or pathological skin. These skin equivalents were constructed using three dermal cell types: normal wound (Wmyo) or hypertrophic wound (Hmyo) myofibroblasts and normal skin fibroblasts (Fb). Epidermis was reconstructed with normal skin keratinocytes (NK) or hypertrophic scar keratinocytes (HK). In the absence of keratinocytes, Hmyo formed a thicker dermis than Wmyo. When seeded with NK, the dermal thickness of Hmyo (121.2 +/- 31.4 microm vs 196.2 +/- 27.8 microm) and Fb (43.7 +/- 7.1 microm vs 83.6 +/- 16.3 microm) dermis was significantly (p < 0.05) reduced, while that of Wmyo (201.5 +/- 15.7 microm vs 160.7 +/- 21.1 microm) was increased. However, the presence of HK always induced significantly thicker dermis formation than observed with NK (Wmyo: 238.8 +/- 25.9 microm; Hmyo: 145.5 +/- 22.4 microm; Fb: 74.2 +/- 11.2 microm). These results correlated with collagen and MMP-1 secretion and with cell proliferation, which were increased when keratinocytes were added, except for the collagen secretion of Hmyo and Fb in the presence of NK. The level of dermal apoptosis was not different when epidermis was added to the dermis (<1% in each category). These observations strongly suggest that hypertrophic scar keratinocytes play a role in the development of pathological fibrosis by influencing the behaviour of dermal cells.

Apoptosis↗

PubMed2002

Toxaphene, but not beryllium, induces human neutrophil chemotaxis and apoptosis via reactive oxygen species (ROS): involvement of caspases and ROS in the degradation of cytoskeletal proteins.

Chemicals of environmental concern are known to alter the immune system. Recent data indicate that some contaminants possess proinflammatory properties by activating neutrophils, an area of research that is still poorly investigated. We have previously documented that toxaphene activates human neutrophils to produce reactive oxygen species (ROS) and accelerates apoptosis by a yet unknown mechanism. In this study, we found that toxaphene induces another neutrophil function, chemotaxis. Furthermore, we found that toxaphene induces both chemotaxis and apoptosis via a ROS-dependent mechanism, since these responses were blocked by the addition of catalase to the culture. In addition, toxaphene was found to induce the degradation of the cytoskeletal proteins gelsolin, paxillin, and vimentin during apoptosis, and this was reversed by the addition of z-VAD-FMK (caspase inhibitor) or catalase, demonstrating the importance of caspases and ROS in this process. In contrast to toxaphene, we found that beryllium does not induce superoxide production, and, this correlates with its inability to induce chemotaxis and apoptosis. We conclude that toxaphene induces chemotaxis and apoptosis via ROS and that caspases and ROS are involved in the degradation of cytoskeletal proteins.

Amino Acid Chloromethyl Ketones↗

PubMed2002

Activation of human neutrophils by the pollutant sodium sulfite: effect on cytokine production, chemotaxis, and cell surface expression of cell adhesion molecules.

We have previously demonstrated that the pollutant sodium sulfite (Na(2)SO(3)) possesses some proinflammatory properties. This study was conducted in order to elucidate how this environmentally significant chemical can alter human neutrophil cell physiology. Using sensitive ELISAs, we found that Na(2)SO(3) induces the total (intra- and extracellular fractions) production of interleukin-12 (IL-12) and IL-8 but not TNF-alpha, IL-1alpha, or IL-4. IL-8 levels were significantly increased in both fractions while the levels of IL-12 were significantly increased only in the extracellular milieu. In contrast, IL-1Ra levels were significantly decreased in both fractions when cells were treated at the highest Na(2)SO(3) concentration (10 mM). Despite the fact that Na(2)SO(3) was found to increase IL-8 production, it does not induce neutrophil chemotaxis in vitro. Cell surface expression of CD18, CD11a, CD11b, CD11c, CD50, and CD54 was not affected by Na(2)SO(3) treatment. We conclude that Na(2)SO(3) is a modulator of cytokine production but that it does not alter either chemotaxis or cell surface expression of the tested molecules. Our results attest to the importance of systematically monitoring cytokine production from both intracellular and extracellular fractions in pollutant-induced neutrophils, since this could lead to different interpretations.

Air Pollutants↗