Biomedical subjects

Kimberly A Woodhouse

Publications and source records attributed to Kimberly A Woodhouse.

10 recordsLinked to original sources

PubMed2006

Development of a model bladder extracellular matrix combining disulfide cross-linked hyaluronan with decellularized bladder tissue.

[Image: see text] In this work we investigate the feasibility of modifying porcine-derived BAM to include HA with a view to developing a model, artificial extracellular matrix for the study of bladder cell-matrix interactions. HA-DPTH was incorporated into BAM disks and then cross-linked oxidatively to a disulfide containing hydrogel. Disks were seeded with bladder smooth muscle cells (BSMC) and UEC under three culture configurations and incubated for 3, 7, and 14 d. At each time point, matrix contraction was measured, and media supernatants assayed for cell-secreted gelatinase activity. To evaluate cell adherence and organization, triple immunofluorescent labeling of cell nuclei, actin cytoskeleton, and focal contacts was performed. HA-modified BAM exhibited a significant increase in matrix contraction and induced a higher level of cell-secreted gelatinase activity compared to unmodified BAM. Immunofluorescent labeling demonstrated that BSMCs remained adherent to both scaffold types over time. The distribution and organization of the cytoskeleton and focal contacts did not appear to be altered by the presence of HA. Interestingly, cellular infiltration into modified BAM was evident by 7 d and continued beyond 14 d, while BSMCs seeded onto unmodified BAM remained localized to the surface out to 14 d, with minimal infiltration evident only at day 28. These differences in cell infiltration support the gelatinase activity results. Increases in cell migration and matrix proteolysis in the presence of HA may be contributing factors toward BAM remodeling leading to increased matrix contraction with time. The model ECM developed in this work will be utilized for future studies aimed at elucidating the mechanisms controlling key remodeling events associated with bladder repair. Matrix contraction of cell-seeded BAM scaffolds.

Animals↗

PubMed2006

Effects of hyaluronan and SPARC on fibroproliferative events assessed in an in vitro bladder acellular matrix model.

Bladder acellular matrix (BAM) is a promising candidate for urinary biomaterials development. In the current work we have modified the BAM construct to include two biologically active components; hyaluronan (HA) and a peptide (SP4.2) derived from secreted protein, acidic, rich in cysteine (SPARC), a matricellular glycoprotein. In order to assess the potential of an HA/SP4.2 modified BAM to influence cellular functions associated with bladder healing, experiments were conducted to evaluate the individual and combined effects of these molecules on in vitro fibroproliferative endpoints within a co-culture model. Thiol-modified HA (246 kDa, 15 mg/ml)+/-SP4.2 (200 microm) was incorporated and cross-linked into BAM disks through disulfide bond formation. The following scaffolds compositions were then evaluated in a bladder smooth muscle cell (SMC)-urothelial (UEC) cell co-culture model: BAM unmodified; BAM+HA, BAM+SP4.2 (media addition); BAM+HA+SP4.2 (media addition); BAM+HA+SP4.2 (matrix incorporated). At 3, 7 and 14 days post-seeding, SMC-mediated matrix contraction and gelatinolytic activity were evaluated. HA-modified BAM exhibited a significantly higher degree of contraction and gelatinase activity compared to unmodified BAM. In contrast, addition of SP4.2 to BAM produced a negligible effect on contraction, while significantly reducing gelatinase activity. Matrices containing both molecules displayed significant increases in contraction, while gelatinase activity was dependent upon the method of peptide delivery. These results demonstrate that both HA and SP4.2 have significant, yet distinct effects on the contractile and proteolytic activity of bladder SMCs and suggest that a modified BAM may be capable of modulating processes associated with post-surgical graft contracture and scar formation.

3T3 Cells↗

PubMed2006

Decellularized placental matrices for adipose tissue engineering.

A tissue-engineered adipose substitute would be invaluable to plastic surgeons for reconstructive, corrective, and cosmetic procedures. This work involves the design of a scaffold for soft tissue augmentation incorporating the decellularized extracellular matrix (ECM) of human placenta. We have developed a protocol to decellularize an intact, large segment (8 cm by 8 cm) of the human placenta. To facilitate the complete decellularization of the dense matrix, a system was designed to perfuse the required chemicals into the placenta via the existing vasculature. Following processing, the original architecture of the placental ECM was preserved, including an intact vascular network. Histological, immunohistochemical, and scanning electron microscopic analyses confirmed the removal of the cells and cellular debris and characterized the composition and structure of the matrix. In vitro cell culture experimentation showed that the placental decellular matrix (PDM) could facilitate the adhesion of primary human adipose precursor cells at early time points. The PDM has great potential for use as a scaffold for adipose tissue engineering, as the placenta is a rich source of human ECM components that can be readily harvested without harm to the donor.

Adipose Tissue↗

PubMed2006

A comparison of human and porcine acellularized dermis: interactions with human fibroblasts in vitro.

BACKGROUND: Dermal substitutes derived from xenograft materials require elaborate processing at a considerable cost. Acellularized porcine dermis is a readily available material associated with minimal immunogenicity. The objective of this study was to evaluate acellularized pig dermis as a scaffold for human fibroblasts. METHODS: In vitro methods were used to evaluate fibroblast adherence, proliferation, and migration on pig acellularized dermal matrix. Acellular human dermis was used as a control. RESULTS: Pig acellularized dermal matrix was found to be inferior to human acellularized dermal matrix as a scaffold for human fibroblasts. Significantly more samples of human acellularized dermal matrix (83 percent, n = 24; p < 0.05) demonstrated fibroblast infiltration below the cell-seeded surface than pig acellularized dermal matrix (31 percent, n = 49). Significantly more (p < 0.05) fibroblasts infiltrated below the surface of human acellularized dermal matrix (mean, 1072 +/- 80 cells per section; n = 16 samples) than pig acellularized dermal matrix (mean, 301 +/- 48 cells per section; n = 16 samples). Fibroblasts migrated significantly less (p < 0.05) distance from the cell-seeded pig acellularized dermal matrix surface than in the human acellularized dermal matrix (78.8 percent versus 38.3 percent cells within 150 mum from the surface, respectively; n = 5). Fibroblasts proliferated more rapidly (p < 0.05) on pig acellularized dermal matrix (n = 9) than on the human acellularized dermal matrix (7.4-fold increase in cell number versus 1.8-fold increase, respectively; n = 9 for human acellularized dermal matrix). There was no difference between the two materials with respect to fibroblast adherence (8120 versus 7436 average adherent cells per section, for pig and human acellularized dermal matrix, respectively; n = 20 in each group; p > 0.05). CONCLUSION: Preliminary findings suggest that substantial differences may exist between human fibroblast behavior in cell-matrix interactions of porcine and human acellularized dermis.

Adolescent↗

PubMed2006

Biological skin substitutes for wound cover and closure.

In the past 30 years, the development and use of artificial skin in the treatment of acute and chronic wounds has advanced from an experimental concept to a working reality. However, while there have been an increasing number of artificial skin substitutes licensed for clinical use, they have yet to supplant the current gold standard of an autologous tissue graft for most applications. This article reviews the advantages and disadvantages of the currently available, biologically based substitutes, with special emphasis on their relative efficacy and suitability for treatment of particular wound types. Economic considerations, desirable improvements of currently available materials and the potential impact of future advances in the field will also be discussed.

Biocompatible Materials↗

PubMed2005

Bladder acellular matrix as a substrate for studying in vitro bladder smooth muscle-urothelial cell interactions.

The objective of this study was to evaluate the ability of bladder acellular matrix (BAM) to support the individual and combined growth of primary porcine bladder smooth muscle (SMC) and urothelial (UEC) cells. An in vitro co-culture system was devised to evaluate the effect of UEC on (i) SMC-mediated contraction of BAM discs, and (ii) SMC invasiveness into BAM. Cells were seeded onto BAM discs under 4 different culture conditions. Constructs were incubated for 1, 7, 14 and 28 days. Samples were then harvested for evaluation of matrix contraction. Immunohistochemistry (IHC) was utilized to examine cellular organization within the samples and conditioned media supernatants analyzed for net gelatinase activity. BAM contraction was significantly increased with co-culture. The same side co-culture configuration lead to a greater reduction in surface area than opposite side co-culture. IHC revealed enhanced SMC infiltration into BAM when co-culture was utilized. A significant increase in net gelatinase activity was also observed with the co-culture configuration. Enhanced infiltration and contractile ability of bladder SMCs with UEC co-culture may, in part, be due to an increase in gelatinase activity. The influence of bladder UECs on SMC behaviour in vitro indicates that BAM may contain some key inductive factors that serve to promote important bladder cell-cell and cell-matrix interactions.

Animals↗

PubMed2004

Investigation of recombinant human elastin polypeptides as non-thrombogenic coatings.

We investigated the use of a recombinant human elastin polypeptide as a coating on synthetic materials with a view to determining if these polypeptides could improve the blood compatibility of cardiovascular devices such as vascular conduits and arterial/venous catheters. Platelet adhesion and activation were studied in vitro using three commercially available synthetic materials: polyethylene terephthalate (Mylar), a poly(tetrafluoroethylene/ethylene) copolymer (Tefzel) and a polycarbonate polyurethane (Corethane). Coated with adsorbed polypeptide, all three synthetic materials demonstrated reduced platelet activation and adhesion in platelet rich plasma in vitro. Compared to non-coated controls, there was a significant decrease (p=0.05) in both platelet microparticle release and P-selectin expression for the polypeptide-coated surfaces. Scanning electron microscopy indicated fewer adhering platelets on coated surfaces compared to non-coated controls. In vivo, in a rabbit model, evaluations of polyurethane catheters coated with the polypeptide showed a marked increase in catheter patency and a significant decrease in fibrin accretion and embolism when compared to uncoated controls. This polypeptide shows a strong potential for use as a non-thrombogenic coating for small diameter vascular grafts. In addition, the results of this study indicate that the elastin polypeptide would be a valuable component of a tissue engineered vascular conduit.

Adsorption↗

PubMed2003

Spatially organized layers of cardiomyocytes on biodegradable polyurethane films for myocardial repair.

Tissue engineering constructs should match the physical and mechanical properties of the native tissue. This implies that pliable scaffolds might be better suited for soft-tissue applications than rigid polymeric materials. In this study, we examined spatially organized cardiomyocyte cultures on biodegradable, elastomeric polyurethane films patterned by microcontact printing of laminin lanes. The resulting cardiomyocyte patterns on polyurethane displayed a similar morphology to those previously achieved for up to 7-10 days on other substrates, such as polystyrene dishes. However, the integrity of the cardiomyocyte patterns on thin, spin-cast or solvent-cast polyurethane films was retained for up to 4 weeks in culture. When additional cardiomyocytes (labeled with Cell Tracker reagents) were seeded onto the patterned cultures, secondary and tertiary cell populations aligned between and on top of the primary patterned cells to form a multilayered, organized tissue construct approximately 2-3 cell layers thick. In addition, dense, highly aligned monolayers of patterned cardiomyocytes were able to contract the thin, solvent-cast polyurethane films. These results indicate that elastomeric, biodegradable polyurethane films can serve as an appropriate scaffold material to support stably the engineering of spatially organized layers of cardiomyocytes in vitro. This approach may serve as a novel method for transplantation of organized cardiac tissue constructs to the heart for myocardial repair.

Animals↗

PubMed2003

Recombinant human elastin polypeptides self-assemble into biomaterials with elastin-like properties.

Processes involving self-assembly of monomeric units into organized polymeric arrays are currently the subject of much attention, particularly in the areas of nanotechnology and biomaterials. One biological example of a protein polymer with potential for self-organization is elastin. Elastin is the extracellular matrix protein that imparts the properties of extensibility and elastic recoil to large arteries, lung parenchyma, and other tissues. Tropoelastin, the approximately 70 kDa soluble monomeric form of elastin, is highly nonpolar in character, consisting essentially of 34 alternating hydrophobic and crosslinking domains. Crosslinking domains contain the lysine residues destined to form the covalent intermolecular crosslinks that stabilize the polymer. We and others have suggested that the hydrophobic domains are sites of interactions that contribute to juxtaposition of lysine residues in preparation for crosslink formation. Here, using recombinant polypeptides based on sequences in human elastin, we demonstrate that as few as three hydrophobic domains flanking two crosslinking domains are sufficient to support a self-assembly process that aligns lysines for zero-length crosslinking, resulting in formation of the crosslinks of native elastin. This process allows fabrication of a polymeric matrix with solubility and mechanical properties similar to those of native elastin.

Biocompatible Materials↗

PubMed2002

Substrate-facilitated assembly of elastin-like peptides: studies by variable-temperature in situ atomic force microscopy.

Extended duration in situ variable-temperature atomic force microscopy performed on a series of coacervating hydrophobic peptides based on human elastin revealed a novel multistage surface assembly process. Formation of epitaxially arranged peptide rods was preceded by rapid expansion of a two-dimensional film on the nucleating substrate, a process facilitated by specific hydrophobic peptide-substrate and intrapeptide interactions.

Base Sequence↗