Regenerative medicine approaches for the reconstitution of missing or injured tissues and organs involves the use of scaffolds, cells, and bioactive molecules. The use of biologic scaffolds seeded with cells is a common approach and several applications have been successfully translated to clinical medicine including lower urinary tract, gastrointestinal tract, musculotendinous, and dermal skin regeneration. The principles that guide tissue remodeling and regeneration are only partially understood but the influence of biomechanical loading upon the remodeling process is accepted as an important variable. However, there is an almost complete absence of systematic, quantitative studies to determine the effect of this controllable factor upon tissue remodeling, especially tissues with a smooth muscle wall component. The present proposal seeks support to conduct a quantitative, hypothesis driven study that determines the effects of mechanical loading upon smooth muscle phenotype in vitro and in vivo and the related changes to the architecture of the scaffold upon which they are seeded. A biologic scaffold derived from the extracellular matrix (ECM) of a porcine urinary bladder will be seeded with smooth muscle cells derived from different sources: the vascular wall, urinary bladder, and esophagus. The influence of those organ specific mechanical loading regimens upon the remodeling process and the ability to modulate the remodeling process by changing the mechanical loading pattern will be investigated.
Two specific aims are described in which: 1) ECM seeded with the three different types of smooth muscle will be subjected to carefully selected mechanical loading regimens and the effect upon cell phenotype and matrix organization will be quantitatively evaluated and 2) two smooth muscle cells types will be evaluated upon ECM used within an organ culture model (rat bladder wall) to evaluate the effect of cellular and ECM remodeling when adjacent normal tissue cells are present. An experienced interdisciplinary team consisting of biomechanical engineers, tissue engineers, physicians, and pathologists has been assembled to conduct these studies. Two consultants, including a leader in the field of regenerative medicine and a statistician, will support this effort. A timeline for completion of these studies, hypotheses to drive the specific aims, alternative approaches for completion of the work, and quantitative criteria for success are provided.

Public Health Relevance

This five year proposal to the National Institutes of Health seeks support to evaluate the effect of mechanical loading upon tissue remodeling, specifically hollow organs rich in smooth muscle tissue. The project will involve two in vitro studies with the use of a biologic scaffold derived from the porcine urinary bladder combined with smooth muscle cells harvested from various sites including the urinary bladder, the vascular wall, and esophagus. The aims of the study are directed at developing quantitative strategies for the use of mechanical loading to optimally drive constructive remodeling of tissues with this regenerative medicine application. The study is being co-directed by Dr. Badylak and Dr. Sacks and is highly interdisciplinary in nature involving a mixture of biomaterials, tissue engineering/regenerative medicine, tissue remodeling, bioengineering, biomechanics, and imaging. An interdisciplinary team consisting of biomechanical engineers, physicians, pathologists, and veterinarians, with consultation from a leader in the field of regenerative medicine, Dr. Anthony Atala, and a statistician, Dr. George McCabe. The work will be conducted at the McGowan Institute for Regenerative Medicine. The work will lead to the creation of functional hollow organs rich in smooth muscle such as the esophagus, intestine, urinary bladder, and arterial vasculature.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Research Project (R01)
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Bioengineering, Technology and Surgical Sciences Study Section (BTSS)
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Hunziker, Rosemarie
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University of Pittsburgh
Schools of Medicine
United States
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Heise, Rebecca L; Parekh, Aron; Joyce, Erinn M et al. (2012) Strain history and TGF-?1 induce urinary bladder wall smooth muscle remodeling and elastogenesis. Biomech Model Mechanobiol 11:131-45
Huber, Alexander; Badylak, Stephen F (2012) Phenotypic changes in cultured smooth muscle cells: limitation or opportunity for tissue engineering of hollow organs? J Tissue Eng Regen Med 6:505-11
Wognum, Silvia; Schmidt, David E; Sacks, Michael S (2009) On the mechanical role of de novo synthesized elastin in the urinary bladder wall. J Biomech Eng 131:101018