Biomedical subjects

C J Doillon

Publications and source records attributed to C J Doillon.

42 records · Page 3Linked to original sources

PubMed1985

Collagen fiber formation in repair tissue: development of strength and toughness.

Dermal repair tissue shows a progressive increase in collagen content which may be related to the wound tensile strength. Wound strength and extensibility are lower than those found in normal skin. In animals, wounds closed by metal clips are chosen as a model to study the proliferative and remodeling phases of healing from a mechanical and morphological point of view. During the proliferative phase the low wound strength is associated with formation of collagen fibers of small diameter, later, (days 28-45) an acute change appears corresponding to the remodeling phase, with increased collagen fiber diameters observed by scanning electron microscopy and light microscopy, and increased tensile strength and toughness. By 180 days, wound strength and collagen fiber morphology were close to that observed in the normal skin. These observations show a direct relationship between collagen fiber diameter and tensile strength. In addition, packing density of collagen fibrils (determined by the birefringence retardation per unit thickness under polarized light) was unchanged until day 90, although collagen fiber diameters increased during this time.

Animals↗

PubMed1985

Collagen deposition during wound repair.

Collagen fiber diameters, amount of birefringent collagen (brightness) and birefringence retardation were measured in implanted collagen-based sponges containing hyaluronic acid (HA) and fibronectin (FN). In the presence of HA and FN, increased number of fibroblasts and brightness were observed 6 days after wounding. Increased brightness in the presence of HA and FN reflected increased deposition of oriented collagen fibers. From days 9 to 12, increased fiber diameters were similar in implanted collagen-based sponges with or without HA and FN. Increased birefringence retardation in sponges containing HA and FN was consistent with increased packing density of collagen fibers observed by scanning electron microscopy. Our results suggest that HA and FN are effective in promoting fibroblast movement into a collagen sponge and deposition of collagen fibers during the early phases of wound healing. Use of a collagen-based sponge containing HA and FN may enhance collagen deposition in situations where healing is compromised as in the case of dermal ulcers.

Animals↗

PubMed1984

Fibroblast-collagen sponge interactions and the spatial deposition of newly synthesized collagen fibers in vitro and in vivo.

Fibroblast-collagen sponge interactions were studied in cell culture and dermal wound systems. In both models fibroblasts appear to adhere, attach and orient in the presence of type I collagen fibrils. In the presence of fibronectin, purified from bovine blood, adhesion and alignment of fibroblasts appeared to be enhanced as well as the deposition of thick collagen fibers. When collagen sponges were grafted onto full thickness dermal wounds the granulation tissue that was laid down within the collagen sponge appeared to differ from granulation tissue laid down below the collagen sponge or on similar wounds in the absence of a sponge. In the absence of a collagen sponge the granulation tissue is characterized by wavy collagen fibers that exhibit an extinction pattern characteristic of crimped fibers found in tendon when examined under polarized light. In contrast, collagen fibers laid down within the sponge appear to be highly oriented and lack evidence of crimp. These results suggest that the presence of a collagen matrix acts as a template that allows for the organized spatial deposition of newly synthesized collagen fibers. The enhanced biosynthesis of thick collagen fibers in the presence of a collagen sponge containing fibronectin may decrease the remodeling phase that is associated with dermal scarring.

Animals↗

PubMedDate not supplied

Development of a flow simulator to study haemodynamic behaviour of natural and artificial blood vessels under physiologic flow conditions.

A new computer-controlled flow simulator has been designed to study the haemodynamic behaviour of natural and artificial blood vessels under physiologic flow conditions. The simulator can generate well characterized and fully developed laminar flow properties. It includes a unique perfusion case that imposes an axial tension on the vessel segment, and a commercial programmable pump to reproduce pulsatile flow rates. Response to high frequency commands was greatly attenuated and displayed a frequency dependent phase angle. Thus, for complex pulsating flow rates containing different frequency components, the system response was significantly distinct from the command. To reproduce physiologic waveforms, the transfer function of the whole system was determined for different amplitudes and frequencies of flow rate excitations. Each input command was compared to the measured flow rate, and the values of the gain and phase angle were evaluated. If the desired flow rate was composed of a sum of n sine wave components, each has a frequency fj and an amplitude Aj, a corrected command signal was then reconstructed by amplifying the attenuated components and advancing those lagged in time. The corrected signal was finally applied as the new command to the pump. The results showed an excellent agreement with physiologic waveforms. Examples of different pulsatile flow experiments to investigate the effects of frequency, pressure, and wall elasticity are presented.

Blood Flow Velocity↗

PubMedDate not supplied

Three-dimensional type I collagen cell culture systems for the study of bone pathophysiology.

Three-dimensional (3-D) type I collagen cell culture systems composed of reconstituted collagen fibres are able to support short- and long-term growth of various cell types, including cancer cell lines, endothelial cells, endometrial cells, hepatocytes, osteoblasts and fibroblasts and to sustain or even enhance cell differentiation, in vitro. In addition, 3-D culture systems have been successfully used in the investigation of complex biological processes, such as angiogenesis, wound healing, tumour invasion and metastasis. The latter suggested that 3-D culture systems have the potential to simulate cell-cell interactions, which take place in tissues under physiological and pathophysiological conditions. This review focuses on the investigational use of 3-D collagen cell culture systems in bone physiology and the pathophysiology of skeletal metastasis.

Animals↗

PubMedDate not supplied

Stromal fibroblasts are required for PC-3 human prostate cancer cells to produce capillary-like formation of endothelial cells in a three-dimensional co-culture system.

The outcome of patients with prostate cancer is largely dependent on the ability of the primary tumor for local invasion, angiogenesis and metastasis. To better understand the cell-cell interactions that participate in prostate cancer neovascularization, we have developed a novel three-dimensional co-culture system. Capillary-like structures were induced in fibrin gel in which collagen gels containing fibroblasts and/or PC-3 human prostate adenocarcinoma cells were sandwiched together. In the presence of collagen-embedded fibroblasts, angiogenesis apparently occurred, while endothelial cells did not survive when only PC-3 cells were embedded in collagen. In contrast, when PC-3 cells were combined with fibroblasts in collagen gel an enhanced formation of capillary-like structure formation was noted, particularly using FGF-2-supplemented medium. In addition, we observed morphological evidence of PC-3 cells and fibroblast invasion into fibrin using this system. Therefore, we conclude that fibroblasts apparently play an important role in angiogenesis and tumor invasion. Furthermore, this novel three-dimensional co-culture is apparently a promising model for studying de novo angiogenesis and tumor invasion in vitro.

Adenocarcinoma↗