K.J. Bundy

Tulane University

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Melissa G. Shettlemore

U.S. Army Engineer Research and Development Center

Fionna Mowat

Exponent (United States)

R. Luedemann

Tulane University

B. A. Rahn

AO Foundation

Kim C. O’Connor

Tulane University

David W. Berzins

Marquette University

Nadim J. Hallab

Rush University Medical Center

R. L. Moses

Louisiana State University Health Sciences Center New Orleans

Clifford J. Williams

Tulane University

Rhett J. Clark

University of Alberta

Cooperative Institutions

Tulane University

AO Foundation

University Medical Center New Orleans

Louisiana State University Health Sciences Center New Orleans

National Institute of Standards and Technology

National Institute of Standards

Georgia Institute of Technology

Texas A&M University

Johns Hopkins University

Xavier University

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Characterization of 75:25 Poly(l-lactide-co-ε-caprolactone) Thin Films for the Endoluminal Delivery of Adipose-Derived Stem Cells to Abdominal Aortic Aneurysms

Tissue Engineering (2006)

Chris A. Burks K.J. Bundy Parwis Fotuhi Eckhard Alt

Abdominal aortic aneurysms occur in 5–7% of men over the age of 60 and their incidence is rising. Current therapies remove the affected tissue or prevent blood flow through the aneurysm, but do not repair the underlying structural changes of the vascular wall. Adipose tissue derived stem cells (ADSCs) seeded on a biodegradable thin film and delivered endoluminally to the aneurysm site could potentially repair the vessel wall, preventing growth and rupture of the aneurysm. In this study, the mechanical and degradation properties of a novel 75:25 poly(l-lactide-co-ε-caprolactone) (PLCL) thin film, as well as, the effects of different surface structures on stem cell adherence and resistance to shear stress was investigated. It was possible to reproducibly create films of consistent physical properties. These films degraded approximately 50% in 6 month, which would be a sufficient time to allow cells to engraft in the aortic wall. Ethylene oxide treatment significantly increased the stiffness and yield stress of the films, which exhibit >700% elongation. Treatment of the films with NaOH and HCl induced the formation of surface texture on the films; however, this texture did not affect stem cell adherence or resistance to delamination by shear stress when compared to nontreated or fibronectin-coated films. These results indicate that PLCL thin films have a sufficient degradation time and mechanical strength to serve as a scaffold in vivo for ADSCs, and that ADSCs seeded on the thin film can withstand a range of physiologic shear stresses.

Caprolactone

10.1089/ten.2006.12.2591

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Citations (38)

Corneal epithelial adhesion strength to tethered‐protein/peptide modified hydrogel surfaces

Journal of Biomedical Materials Research Part A (2004)

Christopher S. Wallace Jean T. Jacob Albert Stoltz Jingjing Bi K.J. Bundy

Abstract In this study, we investigated the suitability of microjet impingement for use on hydrogel materials to determine the cellular adhesion strength of corneal epithelial cells grown on novel hydrogels with extracellular matrix proteins (laminin and/or fibronectin) or a peptide sequence (fibronectin adhesion promoting peptide, FAP) tethered to their surface with poly(ethylene glycol) chains. The deformation of the hydrogel surface in response to the force of the microjet was analyzed both visually and mathematically. After the results of these experiments and calculations determined that no deformation occurred and that the pressure required for indentation (1.25 × 10 6 Pa) was three factors of 10 greater than the maximum pressure of the microjet, the relative mean adhesion strength of primary rabbit corneal epithelial cells grown on the novel poly(2‐hydroxyethyl methacrylate‐ co ‐methacrylic acid) hydrogels was determined and compared with that of the same type of cells grown on control glass surfaces. Only confluent cell layers were tested. Cells grown on control glass surfaces adhered with a mean relative adhesion strength of 488 ± 28 dynes/cm 2 . Under identical conditions, cells grown on laminin‐ and FAP‐tethered hydrogel surfaces were unable to be removed, indicating an adhesion strength greater than 516 dynes/cm 2 . Cells grown on fibronectin‐ and fibronectin/laminin (1:1)‐tethered surfaces showed significantly lower relative adhesion strengths (201 ± 50 and 189 ± 11 dynes/cm 2 , respectively), compared with laminin‐ and FAP‐tethered surfaces ( p = 0.001). Our results demonstrate that the microjet impingement method of cell adhesion analysis is applicable to hydrogel substrates. Additionally, analysis of our test surfaces indicates that fibronectin tethered to this hydrogel in the quantity and by the method used here does not induce stable ligand/receptor bonding to the epithelial cell membrane to the same degree as does laminin or FAP. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 72A: 19–24, 2005

10.1002/jbm.a.30199

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Citations (34)

Toxicity measurement of orthopedic implant alloy degradation products using a bioluminescent bacterial assay

Journal of Biomedical Materials Research (1999)

Melissa G. Shettlemore K.J. Bundy

The toxicity of aqueous metal solutions representative of ionic degradation products from orthopedic implant alloys was determined using a bacterial bioluminescence assay, Microtox®. The toxicity of forms of the individual elements released from ASTM F75 Co-Cr-Mo (Co-Cr-Mo), F138 316L stainless steel (316L), and F136 Ti-6Al-4V (Ti-6Al-4V) was first determined, and a mathematical model was developed to predict the toxicity of mixtures of these ions. Aqueous metal solutions were then mixed according to the proportions of the ions found in these alloys, and their toxicity was measured with Microtox. Mixture behavior was classified as synergistic, antagonistic, or additive by comparing measured toxicity to predicted toxicity. Since relating these tests to actual implant corrosion processes can be confounded by selective leaching, the predicted and measured toxicity of aqueous metal solutions mixed according to proportions representative of selective leaching were next determined, and the mixture behaviors were classified as before. The most toxic individual alloying elements were found to be hexavalent Cr, Ni, and Co, in that order: a finding in accord with prior biocompatibility research. Co-Cr-Mo was found to be the most toxic alloy mixture of both those combined according to alloy composition and those combined to reflect selective leaching. The Ti-6Al-4V mixtures were found to behave synergistically, while the Co-Cr-Mo and 316L mixtures behaved antagonistically. By providing insight into degradation product toxicity and elemental interaction, these experiments demonstrate the utility of employing bioluminescent bacterial assays to investigate biocompatibility of implant materials. Further studies to more closely simulate in vivo conditions, though, are required to fully gauge their potential in this regard. © 1999 John Wiley & Sons, Inc. J Biomed Mater Res, 45, 395–403, 1999.

Biocompatibility

10.1002/(sici)1097-4636(19990615)45:4<395::aid-jbm15>3.0.co;2-h

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Citations (49)

An investigation of the bacteriostatic properties of pure metals

Journal of Biomedical Materials Research (1980)

K.J. Bundy Michael F. Butler R. F. Hochman

Abstract The effect of 16 pure metals on the in vitro growth of a form of dental caries producing Streptococcus mutans was studied under both aerobic and anaerobic conditions. Cobalt and copper were consistently observed to be inhibitory. With less consistency nickel, titanium, iron, and vanadium also exhibited ability to inhibit growth of the organism. Bacteriostasis apparently is contingent upon the presence of a corrosion process. The bacteriostatic agent is of uncertain identity and could be a corrosion product or a process secondary to the occurrence of corrosion. Concentrations of metals after 6 days of electrochemical dissolution in the growth medium were measured via electron microprobe analysis and compared with the amount of inhibition which resulted. Threshold concentrations above which growth did not occur were identified. As measured by threshold concentrations, wide variability between metals exists in the ability to inhibit the growth, with cobalt being particularly effective at small concentrations. This implies a sensitivity on the part of the organism that is different for different metals. The threshold concentration varied between aerobic and anaerobic conditions. Streptococcus mutans appeared more resistant to the effects of the metals under anaerobic conditions even though little difference in the amount of corrosion was detected.

Bacterial growth

10.1002/jbm.820140511

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Citations (63)

Heavy metal concentrations in Louisiana waterways, sediments, and biota

K.J. Bundy David W. Berzins

In this investigation polarographic methods (along with GFAAS and ICP) have been used to study the distribution of lead and chromium in Bayou Trepagnier and Devil`s Swamp. Both laboratory and field research have been conducted. Separation and extraction methodology appropriate for analysis of the contaminants at these sites have been developed. Particular attention has been paid to extraction methods for chromium which do not lead to valence state conversion. The availability of such techniques is essential to take full advantage of polarography, a method capable of performing speciation analysis. The results indicate that there is a very inhomogeneous distribution of heavy metals in these environments. In Devil`s Swamp, for example, separation and analysis of aqueous and variously sized particulate moieties in the water and sediment compartments were conducted to determine the partition of lead between them. The results showed that the average lead content was 14.7 ppb and 19.8 ppm, respectively, in these compartments. Apparently bull frogs in Devil`s Swamp can bioaccumulate lead (compared to the measured water level), since the muscle concentration was found to be about 0.6 ppm. This phenomenon is being investigated in a Xenopus frog laboratory model of heavy metal uptake. The basic methodology validated inmore » this study should be fairly generally applicable to assays of other heavy metals.« less

Biota

Swamp

Polarography

Mercury

Source

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Citations (1)

Cell adhesion to biomaterials: correlations between surface charge, surface roughness, adsorbed protein, and cell morphology.

PubMed (1995)

Nadim J. Hallab K.J. Bundy Kim C. O’Connor Rhett J. Clark R. L. Moses

Adhesion of cells to a biomaterial surface can be a major factor mediating its biocompatibility. In this investigation, jet impingement techniques were used to quantify strength of cellular adhesion to various material surfaces. The metals tested: HS25 (a cobalt-based alloy similar to F75), 316L stainless steel, Ti-6Al-4V, and commercially pure tantalum, exhibited nearly a fivefold increase in adhesion strength above that characteristic of the polymeric materials tested (PTFE, silicone rubber, and HDPE). The present study examines physical and biological factors that might influence fibroblast adhesion to the biomaterial surface. The relation between surface charge and cellular adhesion was investigated in a controlled manner by measuring adhesion strength over a range of charge densities. The cells showed charge and electrical potential-dependent adhesion maxima, suggesting that surface alloying for optimum adherence may be possible. In a preliminary series of experiments adsorbed serum protein layers on a series of materials of differing adherence were investigated using gel electrophoresis to assess protein composition. Analysis of adsorbed proteins revealed little difference in relative abundance or total adsorption quantity. SEM micrographs of cells on Ti-6Al-4V and silicone rubber (high and low adhesion materials, respectively) demonstrated differences in cell morphology and cell density.

Biomaterial

Protein Adsorption

Biocompatibility

Silicone rubber

Morphology

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Citations (138)

Deaeration, pH shift, and surface disruption effects on the corrosion of modular THR alloys

V. Bucalo K.J. Bundy

Recent clinical retrieval studies have shown that extensive attack often occurs in modular total hip replacements (THR's). Proposed causes for the degradation of these implants include galvanic, crevice, and fretting corrosion, as well as combinations of these effects. The research described here is part of an ongoing study to determine the mechanism or mechanisms behind these high rates of attack. DC electrochemical techniques have been employed to conduct short, term studies related to device corrosion and fretting. The results suggest that fretting accelerated crevice corrosion is sufficient but not necessary for severe attack of modular THR's. Crevice conditions alone may cause the attack, if the pH and p/sub O2/ levels decline sufficiently far.

Crevice corrosion

Galvanic cell

Galvanic corrosion

Degradation

10.1109/sbec.1995.514433

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Citations (0)

Evaluation of Metallic and Polymeric Biomaterial Surface Energy and Surface Roughness Characteristics for Directed Cell Adhesion

Tissue Engineering (2001)

Nadim J. Hallab K.J. Bundy Kim C. O’Connor R. L. Moses Joshua J. Jacobs

Directed cell adhesion remains an important goal of implant and tissue engineering technology. In this study, surface energy and surface roughness were investigated to ascertain which of these properties show more overall influence on biomaterial-cell adhesion and colonization. Jet impingement was used to quantify cellular adhesion strength. Cellular proliferation and extracellular matrix secretion were used to characterize colonization of 3T3MC fibroblasts on: HS25 (a cobalt based implant alloy, ASTM F75), 316L stainless steel, Ti-6Al4V (a titanium implant alloy), commercially pure tantalum (Ta), polytetrafluoroethylene (PTFE), silicone rubber (SR), and high-density polyethylene (HDPE). The metals exhibited a nearly five-fold greater adhesion strength than the polymeric materials tested. Generally, surface energy was proportional to cellular adhesion strength. Only polymeric materials demonstrated significant increased adhesion strength associated with increased surface roughness. Cellular adhesion on metals demonstrated a linear correlation with surface energy. Less than half as much cellular proliferation was detected on polymeric materials compared to the metals. However the polymers tested demonstrated greater than twice the amount of secreted extracellular matrix (ECM) proteins on a per cell basis than the metallic materials. Thus, surface energy may be a more important determinant of cell adhesion and proliferation, and may be more useful than surface roughness for directing cell adhesion and cell colonization onto engineered tissue scaffoldings.

Biomaterial

Titanium alloy

10.1089/107632700300003297

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Citations (563)

The effect of surface preparation on metal/bone cement interfacial strength

Journal of Biomedical Materials Research (1987)

K.J. Bundy Robert W. Penn

Abstract This study is concerned with finding practical ways for strengthening metal/bone cement (M/BC) interfaces via surface alterations and identifying fundamental mechanisms underlying M/BC adherence. Shear strengths have been inferred from torsion tests using shear lag analysis. The variables examined with regard to their effects on interfacial strength are substrate material, surface roughness, interface porosity, passivation and sterilization, surface cleaning procedures, and use of bone cement precoated metals. M/BC interfaces can be substantially strengthened by applying the bone cement to the metal with high pressure. This would be a practical way to strengthen interfaces for precoated implants. The acrylic polymerized in vivo would employ the usual low pressure method. Otherwise, the main method for improving M/BC interfaces is through changing surface topography. Cleaning or chemical treatments have relatively minor effects. Roughened surfaces, as expected, produce stronger interfaces. Dramatic strength improvements occurred with a porous arc plasma sprayed layer on the substrate. Surprisingly, highly polished surfaces also improve interface strength (compared to less polished surfaces). The hypothesis is advanced that M/BC adherence depends upon superposition of mechanical interlocking and atomic interaction effects, with the latter predominating for finer finishes and vice versa. Differences exist between materials which are independent of roughness.

Interlocking

10.1002/jbm.820210607

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Citations (58)

Use of a.c. impedance methods to study the corrosion behaviour of implant alloys

Biomaterials (1993)

K.J. Bundy John G. Dillard R. Luedemann

Pitting Corrosion

Nyquist plot

10.1016/0142-9612(93)90242-t

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Citations (21)