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Stephen F Badylak

Publications and source records attributed to Stephen F Badylak.

At least 19 recordsLinked to original sources
PubMed2006

A quantitative method for evaluating the degradation of biologic scaffold materials.

Scaffolds derived from naturally occurring extracellular matrix (ECM) have found extensive use in the fields of tissue engineering and regenerative medicine. Many of these scaffolds are designed to degrade rapidly as they are replaced by new host tissue. Other scaffolds are chemically crosslinked to slow the rate of degradation or add strength to the scaffold. Commercially available ECM scaffolds have considerable variability with regards to tissue origin and methods of processing, and little is known about their rate of degradation and the fate of their degradation products. A novel method is described herein to integrally label ECM with a radioactive isotope ((14)C). It was found that a number of tissues are efficiently labeled, including heart, liver, trachea, pancreas, small intestine, and urinary bladder tissue. Of the tissues analyzed, only spleen was not found to contain detectable levels of (14)C. The technique is extremely sensitive, accurate, and safe, but requires access to accelerator mass spectrometry, and is expensive and time consuming. This model represents the first described quantitative method to determine the rate of degradation for an ECM scaffold and to track the fate of the degradation products.

Animals↗
PubMed2006

Decellularization of tissues and organs.

Decellularized tissues and organs have been successfully used in a variety of tissue engineering/regenerative medicine applications, and the decellularization methods used vary as widely as the tissues and organs of interest. The efficiency of cell removal from a tissue is dependent on the origin of the tissue and the specific physical, chemical, and enzymatic methods that are used. Each of these treatments affect the biochemical composition, tissue ultrastructure, and mechanical behavior of the remaining extracellular matrix (ECM) scaffold, which in turn, affect the host response to the material. Herein, the most commonly used decellularization methods are described, and consideration give to the effects of these methods upon the biologic scaffold material.

Animals↗
PubMed2006

Effect of storage upon material properties of lyophilized porcine extracellular matrix derived from the urinary bladder.

Xenogeneic extracellular matrices (ECMs) have been developed as off-the-shelf biologic scaffolds that have been effectively used in preclinical and clinical applications for tissue reconstruction. Such materials must be suitable for terminal sterilization and capable of storage for extended periods of time without significant changes in material properties and bioactivity. Material properties of interest for ECM scaffolds include hydrostatic permeability index (PI), uniaxial maximum load and elongation, maximum tangential stiffness (MTS), suture retention strength (SRS), and ball-burst strength (BBS). The present study evaluated these material properties for lyophilized forms of an ECM scaffold derived from the porcine urinary bladder, termed urinary bladder matrix (UBM), that was terminally sterilized by e-beam irradiation at 22 kGy and stored at room temperature (RT; 20-24 degrees C) or refrigerated temperature (REFT; 4-8 degrees C) for up to 12 months. UBM devices showed no change in SRS, BBS, and hydrostatic PI after the evaluation period. Lyophilized devices stored at RT showed an increase in maximum load and MTS while devices stored at REFT showed an increase in maximum elongation after 1 year of storage (p < 0.05). These results indicate that structural changes in the UBM device may slowly occur as a function of prolonged storage and storage temperature.

Animals↗
PubMed2006

Extracellular matrix scaffolds are repopulated by bone marrow-derived cells in a mouse model of achilles tendon reconstruction.

The extracellular matrix derived from porcine small intestinal submucosa (SIS-ECM), an FDA-approved material currently used clinically for rotator cuff repair, has been shown to attract bone marrow-derived cells during in vivo remodeling of a subcutaneous implant and produce chemoattractant peptides following chemical degradation in vitro. The purpose of the present study was to determine if bone marrow-derived cells participate in the long-term remodeling of the Achilles tendon in a mouse model when repaired with SIS-ECM. A 2-mm gap was produced in the Achilles tendon of 40 chimeric mice produced to express green fluorescent protein (GFP) in all of their bone marrow-derived cells. Tendons were repaired by replacing the resected section with autologous tendon tissue or with a single layer sheet of lyophilized SIS-ECM. Four animals from each treatment group were sacrificed at 1, 2, 4, 8, and 16 weeks, and sections were harvested for histologic and fluorescence microscopy. Both groups showed accumulation of GFP-expressing marrow-derived cells at the site of tendon remodeling at 1 and 2 weeks that were associated with areas of angiogenesis and inflammation. By 16 weeks, the SIS-ECM-treated group showed GFP expressing cells throughout the remodeled tendon in the absence of any inflammatory response, while the autologous tendon repair group showed no GFP expressing cells within the tendon except for occasional cells in the lumen of blood vessels. An SIS-ECM scaffold used for tendon repair recruits a population of bone marrow-derived cells that participates in the long-term remodeling process. The ability of SIS-ECM to recruit a population of marrow-derived cells to the remodeling site may alter the default mechanism of tendon healing. The involvement of these cells in the remodeling process may explain in part the process of site specific constructive remodeling as opposed to scar tissue formation when the ECM is used as a biologic scaffold for tendon reconstruction.

Achilles Tendon↗
PubMed2006

Reinforcement of esophageal anastomoses with an extracellular matrix scaffold in a canine model.

BACKGROUND: The gastric pull-up procedure, a standard intervention after radical esophagectomy, is associated with high morbidity and mortality due to leaks and stricture. A previous preclinical study showed that an extracellular matrix (ECM) scaffold with autologous muscle tissue could be used to repair a complete circumferential defect in the cervical esophagus. The aim of the present study was to determine if healing of end-to-end anastomoses of the esophagus could be improved by reinforcement with an ECM scaffold. METHODS: Twelve female mongrel dogs underwent a complete transection of either the cervical esophagus (n = 6) or the gastroesophageal junction (n = 6). A portion of the endomucosa at the anastomotic site was resected and replaced with an ECM scaffold in contact with the subjacent muscle and the muscle was anastomosed. The measured end points included macroscopic and microscopic evaluation and quantification of the esophageal diameter at the anastomotic site. RESULTS: No anastomotic leaks or systemic complications were observed in the ECM-treated animals. Morphologic findings in both groups showed complete mucosal covering of the surgery site. The remodeled esophageal tissue showed angiogenesis and complete epithelialization. Intact, organized layers of muscle tissue were present between the native muscularis externa and the submucosal layer and effectively bridged the transected ends. CONCLUSIONS: The ECM scaffold altered the default mechanism of esophageal repair. Scar tissue formation with associated stricture was virtually eliminated, and the esophageal healing response was characterized by the replacement with structurally normal tissue layers. These findings suggest that the high morbidity rate associated with esophagectomy procedures may be reduced by this ECM augmentation procedure at the anastomotic site.

Anastomosis, Surgical↗
PubMed2006

The application of tissue engineering procedures to repair the larynx.

The field of tissue engineering/regenerative medicine combines the quantitative principles of engineering with the principles of the life sciences toward the goal of reconstituting structurally and functionally normal tissues and organs. There has been relatively little application of tissue engineering efforts toward the organs of speech, voice, and hearing. The present manuscript describes a study that was conducted in which a biologic scaffold derived from porcine (pig) extracellular matrix (ECM) was used to repair the defect following a hemilaryngectomy procedure in dogs. The ECM-augmented repair was compared with a control standard strap muscle (STM) procedure. The animals were sacrificed after 24 weeks at which time anatomic and histologic analyses were conducted. The ECM repair resulted in a macroscopic and microscopic reconstruction of laryngeal tissue that was superior to that observed with the STM procedure. The importance of regenerated tissue having the same structural and functional characteristics of native tissue is emphasized. A discussion of the mechanisms of ECM remodeling is presented along with the implications of such remodeling in the repair of laryngeal structures.

Animals↗
PubMed2006

The PediaFlow pediatric ventricular assist device.

The very limited options available to treat ventricular failure in patients with congenital and acquired heart diseases have motivated the development of a pediatric ventricular assist device (VAD). Our effort involves a consortium consisting of the University of Pittsburgh, Carnegie Mellon University, Children's Hospital of Pittsburgh, World Heart Corporation, and LaunchPoint Technologies, LLC. The overall aim of our program is to develop a highly reliable, biocompatible VAD for chronic support (6 months) of the unique and high-risk population of children between 3 kg and 15 kg (patients from birth to 2 years of age). The innovative pediatric VAD we are developing (PediaFlow) is based on a miniature mixed-flow turbodynamic pump featuring magnetic levitation, with the design goal being to assure minimal blood trauma and risk of thrombosis. This article discusses the limitations of current pediatric cardiac assist treatment options and the work to date by our consortium toward the development of a pediatric VAD.

Biocompatible Materials↗
PubMed2006

The basement membrane component of biologic scaffolds derived from extracellular matrix.

The extracellular matrix (ECM) has been successfully used as a scaffold for constructive remodeling of multiple tissues in both preclinical studies and in human clinical applications. The basement membrane is a specialized form of the ECM that supports and facilitates the growth of epithelial cell populations. The morphology and the molecular composition of the ECM, including the basement membrane, vary depending upon the organ from which the ECM is harvested and the methods by which it is processed for use as a medical device. Processing steps, such as decellularization, lyophilization, disinfection, and terminal sterilization, may affect the morphology and composition of an ECM scaffold, including, but not limited to, the integrity of a basement membrane complex. The present study evaluated the presence and integrity of a basement membrane complex in processed ECM derived from three different tissues: the urinary bladder, small intestine, and liver. Immunohistochemical determination of the presence and localization of three basement membrane molecules, collagen IV, laminin, and collagen VII, was conducted for each ECM scaffold. Scanning electron microscopy (SEM) was used to further explore the surface ultrastructure of selected ECM scaffolds. The effect of a surface basement membrane presence upon the pattern of in vitro growth of two separate cell types, NIH 3T3 fibroblasts and human microvascular endothelial cells (HMEC), was also evaluated for each ECM scaffold. Results showed that the only intact basement membrane complex was found on the luminal surface of the ECM derived from the urinary bladder and that the basement membrane was an effective barrier to penetration of the scaffold by the seeded cells. We conclude that the urinary bladder ECM but not the small intestine- or liver-derived ECM contains a surface with composition and morphology consistent with that of an intact basement membrane complex, that the basement membrane complex can survive processing, and that the basement membrane structure can modulate in vitro cell growth patterns.

Animals↗
PubMed2006

Fiber kinematics of small intestinal submucosa under biaxial and uniaxial stretch.

Improving our understanding of the design requirements of biologically derived collagenous scaffolds is necessary for their effective use in tissue reconstruction. In the present study, the collagen fiber kinematics of small intestinal submucosa (SIS) was quantified using small angle light scattering (SALS) while the specimen was subjected to prescribed uniaxial or biaxial strain paths. A modified biaxial stretching device based on Billiar and Sacks (J. Biomech., 30, pp. 753-7, 1997) was used, with a real-time analysis of the fiber kinematics made possible due to the natural translucency of SIS. Results indicated that the angular distribution of collagen fibers in specimens subjected to 10% equibiaxial strain was not significantly different from the initial unloaded condition, regardless of the loading path (p=0.31). Both 10% strip biaxial stretch and uniaxial stretches of greater than 5% in the preferred fiber direction led to an increase in the collagen fiber alignment along the same direction, while 10% strip biaxial stretch in the cross preferred fiber direction led to a broadening of the distribution. While an affine deformation model accurately predicted the experimental findings for a biaxial strain state, uniaxial stretch paths were not accurately predicted. Nonaffine structural models will be necessary to fully predict the fiber kinematics under large uniaxial strains in SIS.

Animals↗
PubMed2006

Extracellular matrix bioscaffolds for orthopaedic applications. A comparative histologic study.

BACKGROUND: Biologic scaffold materials prepared from extracellular matrix are currently available for the surgical repair of damaged or missing musculotendinous tissue. These scaffolds differ in their species and tissue of origin, methods of processing, and methods of terminal sterilization. The purpose of the present study was to evaluate the host-tissue morphologic response to five commercially available extracellular matrix-derived biologic scaffolds used for orthopaedic soft-tissue repair in a rodent model. METHODS: One hundred twenty-six Sprague-Dawley rats were divided into six groups of twenty-one animals each. A defect was created in the musculotendinous tissue of the abdominal wall of each animal and then was repaired with one of five different scaffold materials (GraftJacket, Restore, CuffPatch, TissueMend, Permacol) or with the excised autologous tissue. Three animals from each group were killed at one of seven time-points after surgery (two, four, seven, fourteen, twenty-eight, fifty-six, and 112 days), and the specimens were examined with histologic and morphologic methods. The degree of cellular infiltration, multinucleated giant cell presence, vascularity, and organization of the replacement connective tissue were evaluated with semiquantitative methods. RESULTS: Each device elicited a distinct morphologic response that differed with respect to cellularity (p<0.001), vascularity (p<0.01), the presence of multinucleated giant cells (p<0.01), and organization of the remodeled tissue (p<0.01) at or after the Day 7 time-point. More rapidly degraded devices such as Restore and autologous tissue showed the greatest amount of cellular infiltration, especially at the early time-points. Devices that degraded slowly, such as CuffPatch, TissueMend, and Permacol, were associated with the presence of foreign-body giant cells, chronic inflammation, and/or the accumulation of dense, poorly organized fibrous tissue. CONCLUSIONS: Biologic scaffold materials composed of extracellular matrix elicit distinct host-tissue histologic and morphologic responses, depending on species of origin, tissue of origin, processing methods, and/or method of terminal sterilization.

Animals↗
PubMed2006

The use of extracellular matrix as an inductive scaffold for the partial replacement of functional myocardium.

Regenerative medicine approaches for the treatment of damaged or missing myocardial tissue include cell-based therapies, scaffold-based therapies, and/or the use of specific growth factors and cytokines. The present study evaluated the ability of extracellular matrix (ECM) derived from porcine urinary bladder to serve as an inductive scaffold for myocardial repair. ECM scaffolds have been shown to support constructive remodeling of other tissue types including the lower urinary tract, the dermis, the esophagus, and dura mater by mechanisms that include the recruitment of bone marrow-derived progenitor cells, angiogenesis, and the generation of bioactive molecules that result from degradation of the ECM. ECM derived from the urinary bladder matrix, identified as UBM, was configured as a single layer sheet and used as a biologic scaffold for a surgically created 2 cm2 full-thickness defect in the right ventricular free wall. Sixteen dogs were divided into two equal groups of eight each. The defect in one group was repaired with a UBM scaffold and the defect in the second group was repaired with a Dacron patch. Each group was divided into two equal subgroups (n = 4), one of which was sacrificed 15 min after surgical repair and the other of which was sacrificed after 8 weeks. Global right ventricular contractility was similar in all four subgroups groups at the time of sacrifice. However, 8 weeks after implantation the UBM-treated defect area showed significantly greater (p < 0.05) regional systolic contraction compared to the myocardial defects repaired with by Dacron (3.3 +/- 1.3% vs. -1.8 +/- 1.1%; respectively). Unlike the Dacron-repaired region, the UBM-repaired region showed an increase in systolic contraction over the 8-week implantation period (-4.2 +/- 1.7% at the time of implantation vs. 3.3 +/- 1.3% at 8 weeks). Histological analysis showed the expected fibrotic reaction surrounding the embedded Dacron material with no evidence for myocardial regeneration. Histologic examination of the UBM scaffold site showed cardiomyocytes accounting for approximately 30% of the remodeled tissue. The cardiomyocytes were arranged in an apparently randomly dispersed pattern throughout the entire tissue specimen and stained positive for alpha- sarcomeric actinin and Connexin 43. The thickness of the UBM graft site increased greatly from the time of implantation to the 8-week sacrifice time point when it was approximately the thickness of the normal right ventricular wall. Histologic examination suggested complete degradation of the originally implanted ECM scaffold and replacement by host tissues. We conclude that UBM facilitates a constructive remodeling of myocardial tissue when used as replacement scaffold for excisional defects.

Actinin↗
PubMed2005

Tissue-engineered myocardial patch derived from extracellular matrix provides regional mechanical function.

BACKGROUND: Extracellular matrix (ECM), a tissue-engineered scaffold, recently demonstrated cardiomyocyte population after myocardial implantation. Surgical restoration of myocardium frequently uses Dacron as a myocardial patch. We hypothesized that an ECM-derived myocardial patch would provide a mechanical benefit not seen with Dacron. METHODS AND RESULTS: Using a canine model, a full thickness defect in the right ventricle was repaired with either Dacron or ECM. A third group had no surgery and determined baseline RV function. Eight weeks later, global systolic function was assessed by the preload recruitable stroke work relationship. Regional systolic function was measured by systolic area contraction (SAC), calculated by high density mechanical mapping. Tau was used to assess global diastolic function. Recoil rate and diastolic shear were used as measures of regional diastolic function. After functional data acquisition, tissue was fixed for histological evaluation. Global systolic and diastolic functions were similar at baseline and after ECM and Dacron implantation. Regional systolic function was greater in the ECM group compared with the Dacron group (SAC: 4.1+/-0.9% versus -1.8+/-1.1, P<0.05). Regional diastolic function was also greater in the ECM group (recoil rate (degrees sec(-1)): -44+/-7 versus -17+/-2, ECM versus Dacron; P<0.05). Immunohistochemical analysis revealed cardiomyocytes in the ECM implant region, a finding not seen with Dacron. CONCLUSIONS: At 8 weeks, an ECM-derived tissue-engineered myocardial patch provides regional mechanical function, likely related to cardiomyocyte population. These results are in sharp contrast to Dacron, a commonly used myocardial patch.

Absorbable Implants↗
PubMed2005

Extracellular matrix scaffold for cardiac repair.

BACKGROUND: Heart failure remains a significant problem. Tissue-engineered cardiac patches offer potential to treat severe heart failure. We studied an extracellular matrix scaffold for repairing the infarcted left ventricle. METHODS AND RESULTS: Pigs (n=42) underwent left ventricular (LV) infarction. At 6 to 8 weeks, either 4-layer multilaminate urinary bladder-derived extracellular matrix or expanded polytetrafluoroethlyene (ePTFE) was implanted as full-thickness LV wall patch replacement. At 1-week, 1-month, or 3-month intervals, pigs were terminated. After macroscopic examination, samples of tissue were prepared for histology, immunocytochemistry, and analysis of cell proportions by flow cytometry. One-week and 1-month patches were intact with thrombus and inflammation; at 1 month, there was also tissue with spindle-shaped cells in proteoglycan-rich and collagenous matrix. More alpha-smooth muscle actin-positive cells were present in urinary bladder matrix (UBM) than in ePTFE (22.2+/-3.3% versus 8.4+/-2.7%; P=0.04). At 3 months, UBM was bioresorbed, and a collagen-rich vascularized tissue with numerous myofibroblasts was present. Isolated regions of alpha-sarcomeric actin-positive, intensely alpha-smooth muscle actin-immunopositive, and striated cells were observed. ePTFE at 3 months had foreign-body response with necrosis and calcification. Flow cytometry showed similarities of cells from UBM to normal myocardium, whereas ePTFE had limited cardiomyocyte markers. CONCLUSIONS: Appearance of a fibrocellular tissue that included contractile cells accompanied biodegradation of UBM when implanted as an LV-free wall infarction patch. UBM appears superior to synthetic material for cardiac patching and trends toward myocardial replacement at 3 months.

Absorbable Implants↗
PubMed2005

Thrombospondin-1 mimetic peptide inhibitors of angiogenesis and tumor growth: design, synthesis, and optimization of pharmacokinetics and biological activities.

The heptapeptide 1, NAc-Gly-Val-DIle-Thr-Arg-Ile-ArgNHEt, a structurally modified fragment derived from the second type-1 repeat of thrombospondin-1 (TSP-1), is known to possess antiangiogenic activity. However, therapeutic utility could not be demonstrated because this peptide has a very short half-life in rodents. To optimize the PD/PK profile of 1, we initiated a systematic SAR study. The initial structural modifications were performed at positions 5 and 7 of peptide 1 and at the N- and C-termini. Out of several hundred peptides synthesized, the nonapeptide 5 (ABT-526) emerged as a promising lead. ABT-526 inhibited VEGF-induced HMVEC cell migration and tube formation in the nanomolar range and increased apoptosis of HUAEC cells. ABT-526 showed acceptable PK in rodents, dog, and monkey. ABT-526, when incorporated in an angiogenic pellet implanted in the rat cornea at 10 microM, reduced neovascularization by 92%. Substitution of DalloIle in place of DIle in ABT-526 provided nonapeptide 6 (ABT-510), which was 30-fold less active than ABT-526 in the EC migration but 20-fold more active in the tube formation assay. In comparison to ABT-526, ABT-510 has increased water solubility and slower clearance in dog and monkey. Radiolabeled ABT-510 demonstrated saturable binding to HMVEC cells at 0.02-20 nM concentrations and was displaceable by TSP-1. ABT-510 and ABT-526 were shown to significantly increase apoptosis of HUAEC cells. ABT-510 was effective in blocking neovascularization in the mouse Matrigel plug model and inhibited tumor growth in the mouse Lewis lung carcinoma model. Previous studies had shown that ABT-510 was effective in inhibiting the outgrowth of murine melanoma metastases in syngeneic mice and in blocking the growth of human bladder carcinoma implanted in nude mice. It had been also shown that ABT-510 could regress tumor lesions in pet dogs or cause unexpected stabilization of the disease in advanced canine cancer. ABT-526 and ABT-510 are the first compounds in the class of potent inhibitors of angiogenesis that mimic the antiangiogenic function of TSP-1. ABT-510 is currently in phase II clinical studies.

Angiogenesis Inhibitors↗
PubMed2005

Use of a particulate extracellular matrix bioscaffold for treatment of acquired urinary incontinence in dogs.

OBJECTIVE: To evaluate use of a particulate bioscaffold consisting of the extracellular matrix (ECM) of the urinary bladder from pigs for treatment of acquired urinary incontinence in dogs resistant to medical treatment. DESIGN: Case series. ANIMALS: 9 female dogs with acquired urinary incontinence. PROCEDURE: In 6 dogs, 30 mg of particulate ECM in 1.0 mL of a carrier consisting of glycerin and saline 10.9% NaCI) solution was injected into each of 3 equally spaced sites around the circumference of the internal urethral sphincter via an endoscopic technique. In the remaining 3 dogs (control dogs), 1.0 mL of the carrier alone was injected in 3 equally spaced sites around the circumference of the internal urethral sphincter in a similar manner. RESULTS: For dogs treated with the ECM, median duration of urinary continence following treatment was 168 days (range, 84 to 616 days), whereas for the control dogs, median duration of urinary continence following the procedure was 14 days (range, 7 to 31 days). Two of the 3 control dogs were treated with the ECM at the end of the study and were continent for 119 and 252 days. No adverse effects were observed in any dog. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that endoscopically guided injection of particulate ECM into the internal urethral sphincter may be useful for the treatment of acquired urinary incontinence in female dogs.

Animals↗
PubMed2005

Regenerative medicine and developmental biology: the role of the extracellular matrix.

The principles and ultimate goals of regenerative medicine and developmental biology involve a complex sequence of events, culminating in the formation of structurally and functionally normal tissues and organs. The molecular composition of the extracellular matrix (ECM) plays a critical role in cellular migration and differentiation events. Mammalian ECM, derived from various tissues and organs, has been used as a biologic scaffold for therapeutic regenerative applications. Hundreds of thousands of human patients have benefited from the use of biologic scaffolds composed of naturally occurring ECM. The mechanisms by which ECM induces constructive remodeling instead of scar tissue formation are only beginning to be understood. This article reviews composition of mammalian ECM, its poorly understood role in developmental biology, and the clinical applications that have resulted from the use of this naturally occurring scaffold.

Animals↗
PubMed2005

Production and characterization of ECM powder: implications for tissue engineering applications.

Two methods to produce a particulate form of extracellular matrix (ECM) from porcine urinary bladder were investigated. One method to produce the powder involved snap freezing a lyophilized form of the material and then pulverizing it in a grinding mill. The second method was similar except that the ECM was saturated in a solution of NaCl prior to snap freezing to precipitate salt crystals within the matrix before grinding. Several methods were utilized to analyze the particle size distribution and ultrastructure including sonic sifting, laser diffraction, and scanning electron microscopy (SEM). The salt precipitation method yielded a more uniform distribution of particles with a smaller mean diameter (158 vs. 191 microm). SEM showed that the particles produced by grinding without salt precipitation were irregularly shaped, sheet-like particles. ECM particles produced by the salt precipitation method were round and porous in appearance with many particles in the range of 1 microm which tended to agglomerate with the larger particles and with each other. We conclude that the production of a comminuted form of ECM is possible and that the uniformity of particle size and shape are dependent upon the manufacturing methodology.

Animals↗