Engineering graded tissue interfaces

Abstract

Interfacial zones between tissues provide specialized, transitional junctions central to normal tissue function. Regenerative medicine strategies focused on multiple cell types and/or bi/tri-layered scaffolds do not provide continuously graded interfaces, severely limiting the integration and biological performance of engineered tissue substitutes. Inspired by the bone-soft tissue interface, we describe a biomaterial-mediated gene transfer strategy for spatially regulated genetic modification and differentiation of primary dermal fibroblasts within tissue-engineered constructs. We demonstrate that zonal organization of osteoblastic and fibroblastic cellular phenotypes can be engineered by a simple, one-step seeding of fibroblasts onto scaffolds containing a spatial distribution of retrovirus encoding the osteogenic transcription factor Runx2/Cbfa1. Gradients of immobilized retrovirus, achieved via deposition of controlled poly(L-lysine) densities, resulted in spatial patterns of transcription factor expression, osteoblastic differentiation, and mineralized matrix deposition. Notably, this graded distribution of mineral deposition and mechanical properties was maintained when implanted in vivo in an ectopic site. Development of this facile and robust strategy is significant toward the regeneration of continuous interfacial zones that mimic the cellular and microstructural characteristics of native tissue.

Scaffold-mediated lentiviral transduction for functional tissue engineering of cartilage

“…Our findings extend previous work showing biomaterialmediated gene delivery using viral vectors (20,(40)(41)(42)(43)(44)(45)(46)(47)(48)(49). The majority of this work demonstrated the ability to specify the spatial location of delivered vectors, rather than the induction of tissuespecific differentiation.…”

Image-Based, Fiber Guiding Scaffolds: A Platform for Regenerating Tissue Interfaces

“…There are limited studies for multiple tissue regeneration and interfacial tissue integration for functional constructs of neogenic complexes such as ligament bone or cartilage bone. 5,6,25,44 In recent studies, multi-phasic scaffolds or physical gradient constructs have been investigated as vehicles for facilitating multiple tissue formation within a single system, 7,8 as well as bioactive molecule-induced tissue morphogenesis. 9 Various in vitro approaches emphasize the strong potential of geometric control for tissue regeneration and morphogenesis with diverse types of cells.…”

“…1,2 Although regenerative medicine holds promise as a prominent future therapeutic strategy, only a limited number of studies have achieved success in multipletissue regeneration and functional interfacial tissue integration, as evident in ligament-bone or cartilage-bone complexes. [3][4][5][6] To overcome these therapeutic difficulties, multi-phasic scaffolds or physical gradient constructs have been designed and used for multiple tissue formation within a single system 7,8 as well as for bioactive molecule-induced tissue morphogenesis and regeneration. 9 Various in vitro approaches highlight the importance of geometric control on tissue regeneration/ morphogenesis using a variety of cell types, [10][11][12] but geometric influences on spatiotemporal tissue regeneration and functional healing have had limited assessment in vivo.…”

Anatomically shaped tissue-engineered cartilage with tunable and inducible anticytokine delivery for biological joint resurfacing

“…For scaffold-mediated transduction, PCL hemispheres were coated in 0.002% poly-L-lysine (PLL) (Sigma-Aldrich) overnight. PLL is a cationic polymer that helps immobilize negatively charged viral vectors to the PCL scaffold (53,59,63). Hemispheres were then rinsed in PBS (Gibco) and 200 μL of concentrated lentivirus containing an inducible expression cassette for IL-1Ra, or eGFP was added at a final biological titer of 6 × 10 6 transducing units per milliliter to each hemisphere.…”