![]() ![]() Fibrin Microbeads Loaded with Mesenchymal Cells Support Their Long-Term Survival While Sealed at Room Temperature. Optimization of fibrin scaffolds for differentiation of murine embryonic stem cells into neural lineage cells. Willerth SM, Arendas KJ, Gottlieb DI, Sakiyama-Elbert SE.The effects of soluble growth factors on embryonic stem cell differentiation inside of fibrin scaffolds. Willerth SM, Faxel TE, Gottlieb DI, Sakiyama-Elbert SE.Fibrin as a delivery system for therapeutic drugs and biomolecules. Fibrin: a versatile scaffold for tissue engineering applications. Three-dimensional cell culture matrices: state of the art. Combining stem cells and biomaterial scaffolds for constructing tissues and cell delivery. Biophysics and dynamics of natural and engineered stem cell microenvironments. Keung AJ, Healy KE, Kumar S, Schaffer DV.This work also served as a starting point for combining a range of stem cell types with fibrin scaffolds for other tissue engineering applications. While other groups have combined iPS cells with fibrin glue for treating Ischemic stroke 18, this work represents the first known report of combining iPS cells with fibrin scaffolds for neural tissue engineering applications. 7,16 These scaffolds have also been used successfully for neural tissue engineering applications, specifically the generation of tissue similar to that found in the central nervous system 17. To further increase the stability of these scaffolds, aprotinin (a protease inhibitor) can be used to slow degradation through addition to the cell culture media. Our observations have shown that these scaffolds when seeded with stem cell derived embryoid bodies remain for 2 weeks in vitro before becoming completely degraded. This 3D biomaterial based culture system more accurately mimics the stem cell niche found in vivo and as a result, it can be used to screen biological cues to determine their effects on stem cell differentiation 6. This protocol detailed above provides a method for generating 3D fibrin scaffolds for pluripotent stem cell culture, specifically for mouse embryonic and induced pluripotent stem cells. Other groups have further investigated fibrin scaffolds for a wide range of cell types and applications - demonstrating the versatility of this approach 8-12. These detailed methods rely on fibrinogen concentrations determined to be optimal for embryonic and induced pluripotent stem cell culture. The process takes 2 days to complete, including an overnight dialysis step for the fibrinogen solution to remove citrates that inhibit polymerization. This protocol details the process of polymerizing fibrin scaffolds from fibrinogen solutions using the enzymatic activity of thrombin. Previous work has shown that such scaffolds can be used to successfully culture embryonic stem cells and this scaffold-based culture system can be used to screen the effects of various growth factors on the differentiation of the stem cells seeded inside 6,7. Such scaffolds can be modified using a variety of methods to incorporate controlled release systems for delivering therapeutic factors 5. Fibrin scaffolds, produced by polymerizing the protein fibrinogen obtained from plasma, have been widely investigated for a variety of tissue engineering applications both in vitro and in vivo 4. While synthetic scaffolds can be synthesized to have a greater range of mechanical and chemical properties and often have greater reproducibility, natural biomaterials are often composed of proteins and polysaccharides found in the extracelluar matrix and as a result contain binding sites for cell adhesion and readily support cell culture. 3 A variety of naturally derived and synthetic biomaterial scaffolds have been investigated as 3D environments for supporting stem cell growth. While 2D tissue culture polystrene has been used for the majority of cell culture experiments, 3D biomaterial scaffolds can more closely replicate the microenvironments found in vivo by enabling more accurate establishment of cell polarity in the environment and possessing biochemical and mechanical properties similar to soft tissue. Culturing stem cells inside of 3D biomaterial scaffolds provides a way to accurately mimic these microenvironments, providing an advantage over traditional 2D culture methods using polystyrene as well as a method for engineering replacement tissues 2. Stem cells are found in naturally occurring 3D microenvironments in vivo, which are often referred to as the stem cell niche 1. ![]()
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