Biology subjects

Guilak, F.

Publications and source records attributed to Guilak, F..

3 recordsLinked to original sources

bioRxiv2018

Cartilaginous and osteochondral tissue formation by human mesenchymal stem cells on three-dimensionally woven scaffolds

The development of mechanically functional cartilage and bone tissue constructs of clinically relevant size, as well as their integration with native tissues, remain important challenges for regenerative medicine. The objective of this study was to assess adult human mesenchymal stem cells (MSC) in large, three dimensionally woven poly({varepsilon}-caprolactone) (PCL) scaffolds in proximity to viable bone, both in a nude rat subcutaneous pouch model and under simulated conditions in vitro. In Study I, various scaffold permutations: PCL alone, PCL-bone, \"point-of- care\" seeded MSC-PCL-bone, and chondrogenically pre-cultured Ch-MSC-PCL-bone constructs were implanted in a dorsal, ectopic pouch in a nude rat. After eight weeks, only cells in the Ch- MSC-PCL constructs exhibited both chondrogenic and osteogenic gene expression profiles. Notably, while both tissue profiles were present, constructs that had been chondrogenically pre- cultured prior to implantation showed a loss of glycosaminoglycan (GAG) as well as the presence of mineralization along with the formation of trabecula-like structures. In Study II of the study, the GAG loss and mineralization observed in Study I in vivo were recapitulated in vitro by the presence of either nearby bone or osteogenic culture medium additives but were prevented by a continued presence of chondrogenic medium additives. These data suggest conditions under which adult human stem cells in combination with polymer scaffolds synthesize functional and phenotypically distinct tissues based on the environmental conditions, and highlight the potential influence that paracrine factors from adjacent bone may have on MSC fate, once implanted in vivo for chondral or osteochondral repair.

bioengineering↗

bioRxiv2018

Regulation of Decellularized Tissue Remodeling via Scaffold-Mediated Lentiviral Delivery in Anatomically-Shaped Osteochondral Constructs

Cartilage-derived matrix (CDM) has emerged as a promising scaffold material for tissue engineering of cartilage and bone due to its native chondroinductive capacity and its ability to support endochondral ossification. Because it consists of native tissue, CDM can undergo cellular remodeling, which can promote integration with host tissue and enables it to be degraded and replaced by neotissue over time. However, enzymatic degradation of decellularized tissues can occur unpredictably and may not allow sufficient time for mechanically competent tissue to form, especially in the harsh inflammatory environment of a diseased joint. The goal of the current study was to engineer cartilage and bone constructs with the ability to inhibit aberrant inflammatory processes caused by the cytokine interleukin-1 (IL-1), through scaffold-mediated delivery of lentiviral particles containing a doxycycline-inducible IL-1 receptor antagonist (IL-1Ra) transgene on anatomically-shaped CDM constructs. Additionally, scaffold-mediated lentiviral gene delivery was used to facilitate spatial organization of simultaneous chondrogenic and osteogenic differentiation via site-specific transduction of a single mesenchymal stem cell (MSC) population to overexpress either chondrogenic, transforming growth factor-beta 3 (TGF-{beta}3), or osteogenic, bone morphogenetic protein-2 (BMP-2), transgenes. Controlled induction of IL-1Ra expression protected CDM hemispheres from inflammation-mediated degradation, and supported robust bone and cartilage tissue formation even in the presence of IL-1. In the absence of inflammatory stimuli, controlled cellular remodeling was exploited as a mechanism for fusing concentric CDM hemispheres overexpressing BMP-2 and TGF-{beta}3 into a single bi-layered osteochondral construct. Our findings demonstrate that site-specific delivery of inducible and tunable transgenes confers spatial and temporal control over both CDM scaffold remodeling and neotissue composition. Furthermore, these constructs provide a microphysiological, in vitro, joint, organoid model with site-specific, tunable, and inducible protein delivery systems for examining the spatiotemporal response to pro-anabolic and/or inflammatory signaling across the osteochondral interface.

bioengineering↗

bioRxiv2018

Highly efficient chondrogenic differentiation of human iPSCs and purification via a reporter allele generated by CRISPR-Cas9 genome editing

The differentiation of human induced pluripotent stem cells (hiPSCs) to prescribed cell fates enables the engineering of patient-specific tissue types, such as hyaline cartilage, for applications in regenerative medicine, disease modeling, and drug screening. In many cases, however, these differentiation approaches are poorly controlled and generate heterogeneous cell populations. Here we demonstrate robust cartilaginous matrix production in three unique hiPSC lines using a highly efficient and reproducible differentiation protocol. To purify chondroprogenitors produced by this protocol, we engineered a COL2A1-GFP knock-in reporter hiPSC line by CRISPR-Cas9 genome editing. Purified chondroprogenitors demonstrated an improved chondrogenic capacity compared to unselected populations. The ability to enrich for chrondroprogenitors and generate homogenous matrix without contaminating cell types will be essential for regenerative and disease modeling applications.

cell biology↗