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Weber C, Gokorsch S, Czermak P. Expansion and Chondrogenic Differentiation of Human Mesenchymal Stem Cells. Int J Artif Organs 2018; 30:611-8. [PMID: 17674338 DOI: 10.1177/039139880703000709] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The potential of human mesenchymal stem cells (hMSC) to differentiate into various types of mesenchymal tissue, such as chondrocytes, makes them a potential cell source in cartilage tissue engineering. Because of the requirement of high cell amounts for the generation of cartilage implants or for the extensive experimental studies to investigate the culture parameters, the initial cells have to be expanded, which leads to high population doubling numbers. It is known that hMSC can differentiate into chondrocytes at least up to the 15th population doubling. To monitor the differentiation status, the protein MIA (melanoma inhibitory activity), which is only synthesized by malignant melanomas and chondrocytes, can be used. In this study the chondrogenic differentiation potential of hMSC beyond the 15th population doubling was investigated using MIA as a chondrocyte marker. A chondrogenic potential of hMSC at higher population doubling numbers may be of interest due to the requirement of less frequent isolations of cells. Therefore hMSC were cultured in a monolayer until the 37th population doubling. Cells of different passages were cultured as pellets for two weeks in transforming growth factor (TGF)-β3 containing differentiation medium. The MIA contents in medium on the last three cultivation days were measured for each case using an MIA-ELISA-kit. A significant difference between MIA content in medium of the pellet and non-stimulated monolayer reference cultures was detectable until the 32nd population doubling. In addition, the hMSC were seeded at lower densities to investigate whether the cells may be expanded faster and with less amount of work due to higher population doubling numbers per passage. The reduced inoculation density led to an increased growth rate. (Int J Artif Organs 2007; 30: 611–8)
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Affiliation(s)
- C Weber
- Department of Biotechnology, University of Applied Sciences Giessen-Friedberg, Giessen, Germany
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Hudson KD, Mozia RI, Bonassar LJ. Dose-dependent response of tissue-engineered intervertebral discs to dynamic unconfined compressive loading. Tissue Eng Part A 2015; 21:564-72. [PMID: 25277703 DOI: 10.1089/ten.tea.2014.0174] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Because of the limitations of current surgical methods in the treatment of degenerative disc disease, tissue-engineered intervertebral discs (TE-IVDs) have become an important target. This study investigated the biochemical and mechanical responses of composite TE-IVDs to dynamic unconfined compression. TE-IVDs were manufactured by floating an injection molded alginate nucleus pulposus (NP) in a type I collagen annulus fibrosus (AF) that was allowed to contract for 2 weeks before loading. The discs were mechanically stimulated at a range of strain amplitude (1-10%) for 2 weeks with a duty cycle of 1 h on-1 h off-1 h on before being evaluated for their biochemical and mechanical properties. Mechanical loading increased all properties in a dose-dependent manner. Glycosaminoglycans (GAGs) increased between 2.8 and 2.2 fold in the AF and NP regions, respectively, whereas the hydroxyproline content increased between 1.2 and 1.8 fold. The discs also experienced a 2-fold increase in the equilibrium modulus and a 4.3-fold increase in the instantaneous modulus. Full effects for all properties were seen by 5% strain amplitude. These data suggest that dynamic loading increases the functionality of our TE-IVDs with region-dependent responses using a method that may be scaled up to larger disc models to expedite maturation for implantation.
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Affiliation(s)
- Katherine D Hudson
- 1 Department of Biomedical Engineering, Cornell University , Ithaca, New York
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Tsai TL, Nelson BC, Anderson PA, Zdeblick TA, Li WJ. Intervertebral disc and stem cells cocultured in biomimetic extracellular matrix stimulated by cyclic compression in perfusion bioreactor. Spine J 2014; 14:2127-40. [PMID: 24882152 DOI: 10.1016/j.spinee.2013.11.062] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 05/10/2013] [Accepted: 11/21/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT Intervertebral disc (IVD) degeneration often causes back pain. Current treatments for disc degeneration, including both surgical and nonsurgical approaches, tend to compromise the disc movement and cannot fully restore functions of the IVD. Instead, cell-based IVD tissue engineering seems promising as an ultimate therapy for IVD degeneration. PURPOSE To tissue-engineer an IVD ex vivo as a biological substitute to replace degenerative IVD. STUDY DESIGN An extracellular matrix (ECM) structure-mimetic scaffold, cocultured human IVD cells and human mesenchymal stem cells (hMSCs), and mechanical stimulation were used to biofabricate a tissue-engineered IVD. METHODS An optimal ratio of human annulus fibrosus (hAF) cells to hMSCs for AF generation within aligned nanofibers, and that of human nucleus pulposus (hNP) cells to hMSCs for NP generation within hydrogels were first determined after comparing different coculture ratios of hAF or hNP cells to hMSCs. Nanofibrous strips seeded with cocultured hAF cells/hMSCs were constructed into multilayer concentric rings, enclosing an inner core of hydrogel seeded with hNP cells/hMSCs. A piece of nonwoven nanofibrous mat seeded with hMSC-derived osteoblasts was assembled on the top of the cellular nanofiber/hydrogel assembly, as an interface layer between the cartilagenous end plate and vertebral body. The final assembled construct was then maintained in an osteochondral cocktail medium and stimulated with compressive loading to further enhance the hAF and hNP cells differentiation and increase the IVD ECM production. RESULTS Among all cocultured groups, hAF cells and hMSCs in the ratio of 2:1 cultured in nanofibers showed the closest mRNA expression levels of AF-related markers to positive control hAF cells, whereas hNP cells and hMSCs in the ratio of 1:2 cultured in hydrogels showed the closest expression levels of NP-related markers to positive control hNP cells. The effects of compressive loading on chondrogenesis of hAF or hNP cell and hMSC coculture were dependent on the scaffold structure; the expression of cartilage-related markers in AF nanofibers was downregulated, whereas that in NP hydrogel was upregulated. Interestingly, we found that hMSC-derived osteogenic cells in the interface layer were turned into chondrogenic lineage cells, with decreased expression of osteogenic markers and increased expression of chondrogenic markers. CONCLUSIONS We demonstrate a unique approach using a biomimetic scaffold, IVD and stem cell coculture, and mechanical stimulation to tissue-engineer a biological IVD substitute. The results show that our approach provides both favorable physical and chemical cues through cell-matrix and cell-cell interactions and mechanobiological induction to enhance IVD generation ex vivo. Our findings may lead to viable tissue engineering applications of generating a functional biological IVD for the treatment of disc degeneration.
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Affiliation(s)
- Tsung-Lin Tsai
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1685 Highland Ave, Madison, WI, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, USA
| | - Brenton C Nelson
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1685 Highland Ave, Madison, WI, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, USA
| | - Paul A Anderson
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1685 Highland Ave, Madison, WI, USA
| | - Thomas A Zdeblick
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1685 Highland Ave, Madison, WI, USA
| | - Wan-Ju Li
- Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1685 Highland Ave, Madison, WI, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI, USA.
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Shachar M, Benishti N, Cohen S. Effects of mechanical stimulation induced by compression and medium perfusion on cardiac tissue engineering. Biotechnol Prog 2012; 28:1551-9. [PMID: 22961835 DOI: 10.1002/btpr.1633] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 07/31/2012] [Indexed: 11/12/2022]
Abstract
Cardiac tissue engineering presents a challenge due to the complexity of the muscle tissue and the need for multiple signals to induce tissue regeneration in vitro. We investigated the effects of compression (1 Hz, 15% strain) combined with fluid shear stress (10(-2) -10(-1) dynes/cm(2) ) provided by medium perfusion on the outcome of cardiac tissue engineering. Neonatal rat cardiac cells were seeded in Arginine-Glycine-Aspartate (RGD)-attached alginate scaffolds, and the constructs were cultivated in a compression bioreactor. A daily, short-term (30 min) compression (i.e., "intermittent compression") for 4 days induced the formation of cardiac tissue with typical striation, while in the continuously compressed constructs (i.e., "continuous compression"), the cells remained spherical. By Western blot, on day 4 the expression of the gap junction protein connexin 43 was significantly greater in the "intermittent compression" constructs and the cardiomyocyte markers (α-actinin and N-cadherin) showed a trend of better preservation compared to the noncompressed constructs. This regime of compression had no effect on the proliferation of nonmyocyte cells, which maintained low expression level of proliferating cell nuclear antigen. Elevated secretion levels of basic fibroblast growth factor and transforming growth factor-β in the daily, intermittently compressed constructs likely attributed to tissue formation. Our study thus establishes the formation of an improved cardiac tissue in vitro, when induced by combined mechanical signals of compression and fluid shear stress provided by perfusion.
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Affiliation(s)
- Michal Shachar
- The Avram and Stella Goldstein-Goren Dept. of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer Sheva, Israel.
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See EYS, Toh SL, Goh JCH. Effects of radial compression on a novel simulated intervertebral disc-like assembly using bone marrow-derived mesenchymal stem cell cell-sheets for annulus fibrosus regeneration. Spine (Phila Pa 1976) 2011; 36:1744-51. [PMID: 22046611 DOI: 10.1097/brs.0b013e31821986b3] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN The aim of this study was to develop a tissue engineering approach in regenerating the annulus fibrosus (AF) as part of an overall strategy to produce a tissue-engineered intervertebral disc (IVD) replacement. OBJECTIVE To determine whether a rehabilitative simulation regime on bone marrow–derived mesenchymal stem cell cell-sheet is able to aid the regeneration of the AF. SUMMARY OF BACKGROUND DATA No previous study has used bone marrow–derived mesenchymal stem cell cell-sheets simulated by a rehabilitative regime to regenerate the AF. METHODS The approach was to use bone marrow–derived stem cells to form cell-sheets and incorporating them onto silk scaffolds to simulate the native lamellae of the AF. The in vitro experimental model used to study the efficacy of such a system was made up of the tissue engineering AF construct wrapped around a silicone disc to form a simulated IVD-like assembly. The assembly was cultured within a custom-designed bioreactor that provided a compressive mechanical stimulation onto the silicone disc. The silicone nucleus pulposus would bulge radially and compress the simulated AF to mimic the physiological conditions. The simulated IVD-like assembly was compressed using a rehabilitative regime that lasted for 4 weeks at 0.25 Hz, for 15 minutes each day. RESULTS With the rehabilitative regime, the cell-sheets remained viable but showed a decrease in cell numbers and viability. Gene expression analysis showed significant upregulation of IVD-related genes and there was an increased ratio of collagen type II to collagen type I found within the extracellular matrix. CONCLUSION The results suggested that a rehabilitative regime caused extensive remodeling to take place within the simulated IVD-like assembly, producing extracellular matrix similar to that found in the inner AF.
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Influence of porcine intervertebral disc matrix on stem cell differentiation. J Funct Biomater 2011; 2:155-72. [PMID: 24956302 PMCID: PMC4030937 DOI: 10.3390/jfb2030155] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2011] [Accepted: 08/04/2011] [Indexed: 02/01/2023] Open
Abstract
For back disorders, cell therapy is one approach for a real regeneration of a degenerated nucleus pulposus. Human mesenchymal stem cells (hMSC) could be differentiated into nucleus pulposus (NP)-like cells and used for cell therapy. Therefore it is necessary to find a suitable biocompatible matrix, which supports differentiation. It could be shown that a differentiation of hMSC in a microbial transglutaminase cross-linked gelatin matrix is possible, but resulted in a more chondrocyte-like cell type. The addition of porcine NP extract to the gelatin matrix caused a differentiation closer to the desired NP cell phenotype. This concludes that a hydrogel containing NP extract without any other supplements could be suitable for differentiation of hMSCs into NP cells. The NP extract itself can be cross-linked by transglutaminase to build a hydrogel free of NP atypical substrates. As shown by side-specific biotinylation, the NP extract contains molecules with free glutamine and lysine residues available for the transglutaminase.
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Abstract
A bioreactor is defined as a specifically designed vessel to facilitate the growth of organisms and cells through application of physical and/or electrical stimulus. When cells with therapeutic potential were first discovered, they were initially cultured and expanded in two-dimensional (2-D) culture vessels such as plates or T-flasks. However, it was soon discovered that bioreactors could be used to expand and maintain cultures more easily and efficiently. Since then, bioreactors have come to be accepted as an indispensable tool to advance cell and tissue culture further. A wide array of bioreactors has been developed to date, and in recent years businesses have started supplying bioreactors commercially. Bioreactors in the research arena range from stirred tank bioreactors for suspension culture to those with various mechanical actuators that can apply different fluidic and mechanical stresses to tissues and three-dimensional (3-D) scaffolds. As regenerative medicine gains more traction in the clinic, bioreactors for use with cellular therapies are being developed and marketed. While many of the simpler bioreactors are fit for purpose, others fail to satisfy the complex requirements of tissues in culture. We have examined the use of different types of bioreactors in regenerative medicine and evaluated the application of bioreactors in the realization of emerging cellular therapies.
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Affiliation(s)
- M W Naing
- Healthcare Engineering Research Group, Centre for Biological Engineering, Loughborough University, Loughborough, UK
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Kutty JK, Webb K. Vibration stimulates vocal mucosa-like matrix expression by hydrogel-encapsulated fibroblasts. J Tissue Eng Regen Med 2010; 4:62-72. [PMID: 19842110 DOI: 10.1002/term.219] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The composition and organization of the vocal fold extracellular matrix (ECM) provide the viscoelastic mechanical properties that are required to sustain high-frequency vibration during voice production. Although vocal injury and pathology are known to produce alterations in matrix physiology, the mechanisms responsible for the development and maintenance of vocal fold ECM are poorly understood. The objective of this study was to investigate the effect of physiologically relevant vibratory stimulation on ECM gene expression and synthesis by fibroblasts encapsulated within hyaluronic acid hydrogels that approximate the viscoelastic properties of vocal mucosa. Relative to static controls, samples exposed to vibration exhibited significant increases in mRNA expression levels of HA synthase 2, decorin, fibromodulin and MMP-1, while collagen and elastin expression were relatively unchanged. Expression levels exhibited a temporal response, with maximum increases observed after 3 and 5 days of vibratory stimulation and significant downregulation observed at 10 days. Quantitative assays of matrix accumulation confirmed significant increases in sulphated glycosaminoglycans and significant decreases in collagen after 5 and 10 days of vibratory culture, relative to static controls. Cellular remodelling and hydrogel viscosity were affected by vibratory stimulation and were influenced by varying the encapsulated cell density. These results indicate that vibration is a critical epigenetic factor regulating vocal fold ECM and suggest that rapid restoration of the phonatory microenvironment may provide a basis for reducing vocal scarring, restoring native matrix composition and improving vocal quality.
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Affiliation(s)
- Jaishankar K Kutty
- Department of Bioengineering, Clemson University, Rhodes Research Center, SC 29634, USA
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Nerurkar NL, Baker BM, Sen S, Wible EE, Elliott DM, Mauck RL. Nanofibrous biologic laminates replicate the form and function of the annulus fibrosus. NATURE MATERIALS 2009; 8:986-92. [PMID: 19855383 PMCID: PMC3415301 DOI: 10.1038/nmat2558] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 09/16/2009] [Indexed: 05/20/2023]
Abstract
Successful engineering of load-bearing tissues requires recapitulation of their complex mechanical functions. Given the intimate relationship between function and form, biomimetic materials that replicate anatomic form are of great interest for tissue engineering applications. However, for complex tissues such as the annulus fibrosus, scaffolds have failed to capture their multi-scale structural hierarchy. Consequently, engineered tissues have yet to reach functional equivalence with their native counterparts. Here, we present a novel strategy for annulus fibrosus tissue engineering that replicates this hierarchy with anisotropic nanofibrous laminates seeded with mesenchymal stem cells. These scaffolds directed the deposition of an organized, collagen-rich extracellular matrix that mimicked the angle-ply, multi-lamellar architecture and achieved mechanical parity with native tissue after 10 weeks of in vitro culture. Furthermore, we identified a novel role for inter-lamellar shearing in reinforcing the tensile response of biologic laminates, a mechanism that has not previously been considered for these tissues.
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Affiliation(s)
| | | | | | | | | | - Robert L. Mauck
- Correspondence should be addressed to R.L.M. Phone: 215-898-8653; Facsimile: 215-573-2133 ()
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Freimark D, Czermak P. Cell-based regeneration of intervertebral disc defects: review and concepts. Int J Artif Organs 2009; 32:197-203. [PMID: 19569027 DOI: 10.1177/039139880903200403] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
During the last century low back pain has emerged as a widespread disease often caused by intervertebral disc degeneration (IDD). IDD is a complex problem in which a variety of causes play a role. As IDD causes high costs, corporate interest has led to a number of therapies being developed. Today, these therapies focus not only on minimizing the pain caused by this disease but also on restoring intervertebral disc function. These approaches are often biological and aim to stimulate the regeneration of the intervertebral disc by injection of activator proteins, biomaterials, different cell types or complex cell matrix composites. Genetic engineering of disc cells and in vitro tissue engineering also offer a possibility for curing IDD. This article gives an overview of these concepts.
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Affiliation(s)
- Denise Freimark
- Institute of Biopharmaceutical Technology, University of Applied Sciences Giessen-Friedberg, Giessen, Germany.
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Ferdous Z, Lazaro LD, Iozzo RV, Höök M, Grande-Allen KJ. Influence of cyclic strain and decorin deficiency on 3D cellularized collagen matrices. Biomaterials 2008; 29:2740-8. [PMID: 18394699 DOI: 10.1016/j.biomaterials.2008.03.018] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Accepted: 03/18/2008] [Indexed: 11/15/2022]
Abstract
Cyclic strain evokes the expression of the small leucine-rich proteoglycans decorin and biglycan in 2D cultures and native tissues. However, strain-dependent expression of these proteoglycans has not been demonstrated in engineered tissues. We hypothesized that the absence of decorin may compromise the effect of cyclic strain on the development of engineered tissues. Thus, we investigated the contribution of decorin to tissue organization in cyclically strained collagen gels relative to statically cultured controls. Decorin null (Dcn(-/-)) and wild-type murine embryonic fibroblasts were seeded within collagen gels and mechanically conditioned using a Flexcell Tissue Train culture system. After 8 days, the cyclically strained samples demonstrated greater collagen fibril density, proteoglycan content, and material strength for both cell types. On the other hand, increases in cell density, collagen fibril diameter, and biglycan expression were observed only in the cyclically strained gels seeded with Dcn(-/-) cells. Although cyclic strain caused an elevation in proteoglycan expression regardless of cell type, the type of proteoglycan differed between groups: the Dcn(-/-) cell-seeded gels produced an excess of biglycan not found in the wild-type controls. These results suggest that decorin-mediated tissue organization is strongly dependent upon tissue type and mechanical environment.
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Affiliation(s)
- Zannatul Ferdous
- Department of Bioengineering, Rice University, P.O. Box 1892, MS 142, Houston, TX 77251-1892, USA
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Pörtner R, Goepfert C, Wiegandt K, Janssen R, Ilinich E, Paetzold H, Eisenbarth E, Morlock M. Technical Strategies to Improve Tissue Engineering of Cartilage-Carrier-Constructs. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2008. [DOI: 10.1007/10_2008_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Nerurkar NL, Elliott DM, Mauck RL. Mechanics of oriented electrospun nanofibrous scaffolds for annulus fibrosus tissue engineering. J Orthop Res 2007; 25:1018-28. [PMID: 17457824 DOI: 10.1002/jor.20384] [Citation(s) in RCA: 164] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Engineering a functional replacement for the annulus fibrosus (AF) of the intervertebral disc is contingent upon recapitulation of AF structure, composition, and mechanical properties. In this study, we propose a new paradigm for AF tissue engineering that focuses on the reconstitution of anatomic fiber architecture and uses constitutive modeling to evaluate construct function. A modified electrospinning technique was utilized to generate aligned nanofibrous polymer scaffolds for engineering the basic functional unit of the AF, a single lamella. Scaffolds were tested in uniaxial tension at multiple fiber orientations, demonstrating a nonlinear dependence of modulus on fiber angle that mimicked the nonlinearity and anisotropy of native AF. A homogenization model previously applied to native AF successfully described scaffold mechanical response, and parametric studies demonstrated that nonfibrillar matrix, along with fiber connectivity, are key contributors to tensile mechanics for engineered AF. We demonstrated that AF cells orient themselves along the aligned scaffolds and deposit matrix that contributes to construct mechanics under loading conditions relevant to the in vivo environment. The homogenization model was applied to cell-seeded constructs and provided quantitative measures for the evolution of matrix and interfibrillar interactions. Finally, the model demonstrated that at fiber angles of the AF (28 degrees -44 degrees ), engineered material behaved much like native tissue, suggesting that engineered constructs replicate the physiologic behavior of the single AF lamella. Constitutive modeling provides a powerful tool for analysis of engineered AF neo-tissue and native AF tissue alike, highlighting key mechanical design criteria for functional AF tissue engineering.
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Affiliation(s)
- Nandan L Nerurkar
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, 424 Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, Pennsylvania 19104-6081, USA
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