2011 — 2015 |
Shen, Wei |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
A Novel Cell Release Method For Affinity-Based Cell Separation @ University of Minnesota-Twin Cities
1134148 Shen This NSF award by the Chemical and Biological Separations program supports work by Professor Wei Shen to develop a novel platform to efficiently detach affinity-captured cells with minimal biochemical and biophysical perturbation. Cell separation is essential in many clinical practices and biomedical studies, ranging from disease diagnosis and prognosis to cell-based therapy and fundamental investigations of stem cell biology. Cell separation mediated by the affinity between a cell surface biomarker and a complementary ligand immobilized on a material is label-free and highly specific, and therefore is particularly attractive. However, this method has been limited by the difficulty in efficiently detaching captured cells in a viable and unperturbed state due to the multivalent nature of cell-material interactions. Although this limitation is not an issue for diagnostic and prognostic applications, it is a major challenge when rare, sensitive cells need to be isolated and recovered for use in an unperturbed and functional state, such as stem-cell-based therapy. To fully unleash the potential of label-free, affinity-based cell separation, new cell detachment methods must be developed. In this project, we will harness self-assembly of biopolymers to bring polyethylene glycol (PEG) to the material surface after cell capture, so that multivalent cell-substrate interactions can be disrupted for efficient release of affinity-captured cells due to the conformational energy of extended PEG chains. Successful completion of this project will lead to a novel cell detachment method that, together with label-free and highly specific affinity capture, will allow cell separation to be performed with unprecedented collective quality in terms of high specificity, high yield, and minimal perturbation on cells. This cell detachment platform can be readily adapted for affinity cell separation based on various cell surface biomarkers. The method is compatible with various formats of cell separation: either small-scale operation in microfluidic devices or large-scale affinity chromatography; either flat affinity substrates or bead-based affinity matrices.
This project will provide interdisciplinary training opportunities for graduate and undergraduate students. Such training opportunities are important for preparing a qualified workforce in the field of biomedical engineering, which is one of the major driving forces for the health care industries. Through this project, the PI will promote the research activities of undergraduate students, in particular underrepresented minority and women students, in her laboratory through various programs. The PI will participate in K-12 outreach activities to stimulate interest in biomolecular engineering, biomaterials engineering, and regenerative medicine among young students and inspire more students to pursue careers in these fields.
|
0.951 |
2011 — 2012 |
Shen, Wei |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Modular Assembly Approach to Engineer Prevascularized Large 3d Tissue Constructs @ University of Minnesota
DESCRIPTION (provided by applicant): Tissue engineering holds great promise in creating functional tissues that can replace diseased or lost tissues of human beings. Recently, consensus has been reached that three-dimensional (3D) tissue culture is superior to traditional two-dimensional (2D) cell culture in recapitulating the in vivo cell microenvironments and tissue structures. It has been found that many engineered tissues are functional only when they are developed in 3D systems. Despite the recognized importance of 3D tissue engineering and the tremendous efforts that have been made, the progress of developing large and viable 3D tissues of clinically relevant sizes has been limited. One major challenge in creating such tissue products is insufficient mass transfer in the interior region of large and a vascular constructs. Although mass transfer in large constructs prepared from preformed porous scaffolds can be enhanced in vitro through perfusion culture, insufficient mass transfer remains a problem after these constructs are implanted in vivo. On the other hand, some in situ forming hydrogels allow encapsulated endothelial cells to form capillary networks that undergo an anastomosis with the host vasculature after implantation, but hydrogel constructs without large pores cannot be perfusion-cultured so that their size is limited. Lack of methods to create large perfusable hydrogel constructs supporting in vitro endothelial capillary morphogenesis for prevascularization limits our ability to address the problem of insufficient mass transfer in 3D tissue engineering. The objective of this R21 application is to use a modular assembly approach to develop large, porous hydrogel constructs containing endothelial capillary networks and to examine postimplantation survival of the cells in these constructs. The central hypothesis of this work is that fibrin microgels having well-controlled morphology and laden with endothelial cells and other cells of interest can be modularly assembled into large, porous constructs in situ through a judiciously selected chemical reaction occurring under physiologically permissive conditions and such assembled constructs can be perfusion- cultured in vitro and develop into prevascularized, porous constructs that support high postimplantation cell survival. The Specific Aims of this project are: (1) design, fabrication, and characterization of modularly assembled large porous fibrin hydrogels laden with human umbilical vein endothelial cells (HUVECs) and hMSCs;(2) in vitro culture of large porous cell-laden constructs under perfusion and characterization of capillary morphogenesis and cell viability;(3) implantation of prevascularized porous constructs and characterization of in vivo function of the capillary networks and postimplantation survival of transplanted cells. The method proposed in this application will provide a platform to create centimeter-sized porous constructs containing capillary networks that undergo anastomosis with the host vasculature after implantation and allow interstitial flow of body fluids. Successful accomplishment of this project will address the problem of insufficient mass transfer that hampers creation of functional 3D tissue products of clinically relevant sizes. (End of Abstract)
|
0.958 |
2012 — 2018 |
Shen, Wei |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Career: Multifunctional Dynamic Surfaces For Engineering Cell Microenvironments @ University of Minnesota-Twin Cities
ID: MPS/DMR/BMAT(7623) 1151529 PI: Shen, Wei ORG: University of Minnesota
Title: CAREER: Multifunctional Dynamic Surfaces for Engineering Cell Microenvironments
INTELLECTUAL MERIT: Using synthetic materials to engineer artificial cell microenvironments that recapitulate the essential characteristics of their in vivo counterparts to guide stem cell fate selection has become an important strategy in regenerative medicine. However, it remains a challenge to create materials that mimic dynamic presentation of insoluble ligands, limiting the ability to control and study stem cell fate selection in well-defined biomimetic cell microenvironments. The goal of the project is to develop a method to engineer dynamic biomaterials that enable reversible and orthogonal regulation of multiple insoluble ligands to cell surface receptors without exposing cells to the soluble counterparts of the ligands and to use such engineered materials to study mesodermal differentiation of human induced pluripotent stem cells (iPSCs) in cell microenvironments presenting dynamically controlled integrin ligands as a model system. The specific objectives of this proposal are: (1) design, preparation, and physical-chemical characterization of substrates capable of presenting multiple insoluble ligands reversibly and orthogonally, (2) investigation of reversible and orthogonal regulation of cell-accessible and cell-inaccessible states of the insoluble ligands, (3) investigation of mesodermal differentiation of human iPSCs toward myocardial and hemato-endothelial progenitors in response to dynamically modulated ligands for two specific integrins. Completion of this project will bridge the gap between the need for understanding and controlling stem cell fate selection in response to dynamically modulated insoluble ligands and the lack of enabling dynamic biomaterials. Multifunctional dynamic biomaterials based on this method will allow creation of cell microenvironments that better emulate their in vivo counterparts. These biomimetic artificial cell microenvironments will not only guide more efficient stem cell differentiation toward desired lineages for cell-based therapy, but also enable the study of fundamentals of developmental biology in well-controlled systems, which is difficult to access with animal studies.
BROADER IMPACTS: The approach developed in this project can be adapted for dynamic modulation of many insoluble ligands of interest to construct a variety of biomimetic cell microenvironments. Study and control of cell behavior, fate selection, and functions in these engineered systems will have implications for both technological development and fundamental understandings. The proposed education activities, aimed at creation of a qualified and diversified workforce in the biomaterials and tissue engineering fields, will be completely integrated with the PI's research interests. The PI will give hands-on demonstrations of smart biomaterials (glucose-sensitive gels, temperature-responsive materials for engineering cell sheets, hydrogels allowing cell encapsulation), a seminar on smart biomaterials, and summer research opportunities to the students in the Minneapolis Public Schools High Tech Girls Society and the Exploring Careers in Engineering and Physical Science programs. She will promote the research activities of underrepresented minority and women undergraduate students through participation in the North Star STEM program, and she will help to establish a strong Biomaterials and Tissue Engineering track in the Biomedical Engineering curriculum at the University of Minnesota.
|
0.951 |
2012 — 2013 |
Shen, Wei |
R21Activity Code Description: To encourage the development of new research activities in categorical program areas. (Support generally is restricted in level of support and in time.) |
Nanoscale Assembly of Bioactive Ligands to Enhance Endothelial Differentiation @ University of Minnesota
DESCRIPTION (provided by applicant): Endothelial cells have important biomedical applications ranging from enhancing the patency of engineered vascular grafts and stents to promoting neovascularization in ischemic tissues. But their limited availability hinders the success of endothelial-cell-related technologies. The advances in stem cell technology offer a unique opportunity to address this issue. In particular, endothelial cells have been derived from human pluripotent stem cells (hPSCs), which can proliferate extensively and virtually provide an unlimited cell source. The recent success in making induced PSCs (iPSCs) offers additional advantages in providing immunologically compatible autologous hPSCs and enabling personalized therapy in the future. The key to exploiting this opportunity to advance endothelial-cell-related technologies is our ability to guide endothelial differentiation. In currently used methods, hPSCs are differentiated into hemangioblasts, which have both hematopoietic and endothelial potentials, followed by differentiation of hemangioblasts into endothelial cells in the presence of VEGF and fibronectin(FN)-coated surfaces. VEGF and FN are both essential for efficient endothelial differentiation, and they exhibit a synergistic effect due to the unique structure of FN, which has a cell-adhesive site and a VEGF-binding site positioned in nanoscale proximity. However, naturally-derived FN has batch-to-batch variations. In addition, covalently immobilized FN has structural change that blocks the cell- adhesive ligand; physically adsorbed FN preserves the active cell-adhesive domain but does not allow precise control of surface ligand density. Therefore, cell microenvironments created with FN are not tightly controlled, hampering consistent production of endothelial cells from stem cells. This problem can be addressed by using well-controlled synthetic materials that recapitulate the essential molecular structure underlying the synergistic effect of VEGF and FN in regulating endothelial differentiation. The objective of this application is to develop synthetic materials having the essential structural characteristics underlying the synergistic effect of VEGF and FN and to use these materials to guide endothelial differentiation of human iPSC-derived hemangioblasts. Our central hypothesis is that a cell-adhesive peptide and a VEGF-mimetic peptide fused to a pair of heterodimerizing coiled-coils, respectively, can be brought into nanoscale proximity through coiled-coil self- assembly and the materials functionalized with the heterodimer, together with soluble factors, will create well- controlled cell microenvironments for efficient and reproducible endothelial differentiation of iPSC-derived hemangioblasts. The specific aims are: (1) design, synthesize, characterize, and immobilize the polypeptides that self-assemble to present a cell-adhesive peptide and a VEGF-mimetic peptide in nanoscale proximity; (2) examine endothelial differentiation of human iPSC-derived hemangioblasts on the polypeptide-functionalized substrates. Successful completion of this project will result in well-controlled, biomimetic cell microenvironments for efficient and robust endothelial differentiation of iPSC-derived hemangioblasts. PUBLIC HEALTH RELEVANCE: The proposed project aims to engineer rationally designed, well-controlled synthetic cell microenvironments to guide efficient and reproducible endothelial differentiation of hemangioblasts derived from human induced pluripotent stem cells. Such derived endothelial cells will have important biomedical applications ranging from enhancing the patency of engineered vascular grafts and stents to promoting neovascularization in ischemic tissues.
|
0.958 |