Non-Destructive Reflectance Mapping of Collagen Fiber Alignment in Heart Valve Leaflets.

Collagen fibers are the primary structural elements that define many soft-tissue structure and mechanical function relationships, so that quantification of collagen organization is essential to many disciplines. Current tissue-level collagen fiber imaging techniques remain limited in their ability to quantify fiber organization at macroscopic spatial scales and multiple time points, especially in a non-contacting manner, requiring no modifications to the tissue, and in near real-time. Our group has previously developed polarized spatial frequency domain imaging (pSFDI), a reflectance imaging technique that rapidly and non-destructively quantifies planar collagen fiber orientation in superficial layers of soft tissues over large fields-of-view.

Temporal Impact of Substrate Anisotropy on Differentiating Cardiomyocyte Alignment and Functionality.

Anisotropic biomaterials can affect cell function by driving cell alignment, which is critical for cardiac engineered tissues. Recent work, however, has shown that pluripotent stem cell-derived cardiomyocytes may self-align over long periods of time. To determine how the degree of biomaterial substrate anisotropy impacts differentiating cardiomyocyte structure and function, we differentiated mouse embryonic stem cells to cardiomyocytes on nonaligned, semialigned, and aligned fibrous substrates and evaluated cell alignment, contractile displacement, and calcium transient synchronicity over time.

Electrospun poly(N-isopropyl acrylamide)/poly(caprolactone) fibers for the generation of anisotropic cell sheets.

Cell alignment in muscle, nervous tissue, and cartilage is requisite for proper tissue function; however, cell sheeting techniques using the thermosensitive polymer poly(N-isopropyl acrylamide) (PNIPAAm) can only produce anisotropic cell sheets with delicate and resource-intensive modifications. We hypothesized that electrospinning, a relatively simple and inexpensive technique to generate aligned polymer fibers, could be used to fabricate anisotropic PNIPAAm and poly(caprolactone) (PCL) blended surfaces that both support cell viability and permit cell sheet detachment via PNIPAAm dissolution. Aligned electrospun PNIPAAm/PCL fibers (0%, 25%, 50%, 75%, 90%, and 100% PNIPAAm) were electrospun and characterized.

Maintenance of HL-1 cardiomyocyte functional activity in PEGylated fibrin gels.

Successful cellular cardiomyoplasty is dependent on biocompatible materials that can retain the cells in the myocardium in order to promote host tissue repair following myocardial infarction. A variety of methods have been explored for incorporating a cell-seeded matrix into the heart, the most popular options being direct application of an injectable system or surgical implantation of a patch. Fibrin-based gels are suitable for either of these approaches, as they are biocompatible and have mechanical properties that can be tailored by adjusting the initial fibrinogen concentration.

Device-based in vitro techniques for mechanical stimulation of vascular cells: a review.

The most common cause of death in the developed world is cardiovascular disease. For decades, this has provided a powerful motivation to study the effects of mechanical forces on vascular cells in a controlled setting, since these cells have been implicated in the development of disease. Early efforts in the 1970 s included the first use of a parallel-plate flow system to apply shear stress to endothelial cells (ECs) and the development of uniaxial substrate stretching techniques (Krueger et al.

Multilayer microfluidic PEGDA hydrogels.

Development of robust 3D tissue analogs in vitro is limited by passive, diffusional mass transport. Perfused microfluidic tissue engineering scaffolds hold the promise to improve mass transport limitations and promote the development of complex, metabolically dense, and clinically relevant tissues. We report a simple and robust multilayer replica molding technique in which poly(dimethylsiloxane) (PDMS) and poly(ethylene glycol) diacrylate (PEGDA) are serially replica molded to develop microfluidic PEGDA hydrogel networks embedded within independently fabricated PDMS housings.