Karen Dubbin | Stanford University (original) (raw)

Address: Stanford, California, United States

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Papers by Karen Dubbin

Research paper thumbnail of Spatially Controlled 3D Printing of Dual‐Curing Urethane Elastomers

Advanced Materials Technologies

Research paper thumbnail of Macromolecular gelatin properties affect fibrin microarchitecture and tumor spheroid behavior in fibrin-gelatin gels

Research paper thumbnail of Designer, injectable gels to prevent transplanted Schwann cell loss during spinal cord injury therapy

Science Advances

Transplantation of patient-derived Schwann cells is a promising regenerative medicine therapy for... more Transplantation of patient-derived Schwann cells is a promising regenerative medicine therapy for spinal cord injuries; however, therapeutic efficacy is compromised by inefficient cell delivery. We present a materials-based strategy that addresses three common causes of transplanted cell death: (i) membrane damage during injection, (ii) cell leakage from the injection site, and (iii) apoptosis due to loss of endogenous matrix. Using protein engineering and peptide-based assembly, we designed injectable hydrogels with modular cell-adhesive and mechanical properties. In a cervical contusion model, our hydrogel matrix resulted in a greater than 700% improvement in successful Schwann cell transplantation. The combination therapy of cells and gel significantly improved the spatial distribution of transplanted cells within the endogenous tissue. A reduction in cystic cavitation and neuronal loss were also observed with substantial increases in forelimb strength and coordination. Using an ...

Research paper thumbnail of Comparative Molecular Analysis of Cancer Behavior Cultured In Vitro, In Vivo, and Ex Vivo

Cancers

Current pre-clinical models of cancer fail to recapitulate the cancer cell behavior in primary tu... more Current pre-clinical models of cancer fail to recapitulate the cancer cell behavior in primary tumors primarily because of the lack of a deeper understanding of the effects that the microenvironment has on cancer cell phenotype. Transcriptomic profiling of 4T1 murine mammary carcinoma cells from 2D and 3D cultures, subcutaneous or orthotopic allografts (from immunocompetent or immunodeficient mice), as well as ex vivo tumoroids, revealed differences in molecular signatures including altered expression of genes involved in cell cycle progression, cell signaling and extracellular matrix remodeling. The 3D culture platforms had more in vivo-like transcriptional profiles than 2D cultures. In vivo tumors had more cells undergoing epithelial-to-mesenchymal transition (EMT) while in vitro cultures had cells residing primarily in an epithelial or mesenchymal state. Ex vivo tumoroids incorporated aspects of in vivo and in vitro culturing, retaining higher abundance of cells undergoing EMT wh...

Research paper thumbnail of Quantitative criteria to benchmark new and existing bio-inks for cell compatibility

Research paper thumbnail of 3D Bioprinting: Dual-Stage Crosslinking of a Gel-Phase Bioink Improves Cell Viability and Homogeneity for 3D Bioprinting (Adv. Healthcare Mater. 19/2016)

Advanced Healthcare Materials, 2016

Research paper thumbnail of Dual-Stage Crosslinking of a Gel-Phase Bioink Improves Cell Viability and Homogeneity for 3D Bioprinting

Advanced healthcare materials, 2016

Current bioinks for cell-based 3D bioprinting are not suitable for technology scale-up due to the... more Current bioinks for cell-based 3D bioprinting are not suitable for technology scale-up due to the challenges of cell sedimentation, cell membrane damage, and cell dehydration. A novel bioink hydrogel is presented with dual-stage crosslinking specifically designed to overcome these three major hurdles. This bioink enables the direct patterning of highly viable, multicell type constructs with long-term spatial fidelity.

Research paper thumbnail of A photoactivated nanofiber graft material for augmented Achilles tendon repair

Lasers in Surgery and Medicine, 2012

Background and Objective: Suture repair of Achilles tendon rupture can cause infection, inflammat... more Background and Objective: Suture repair of Achilles tendon rupture can cause infection, inflammation and scarring, while prolonged immobilization promotes adhesions to surrounding tissues and joint stiffness. Early mobilization can reduce complications provided the repair is strong enough to resist re-rupture. We have developed a biocompatible, photoactivated tendon wrap from electrospun silk (ES) to provide additional strength to the repair that could permit early mobilization, and act as a barrier to adhesion formation. Study Design/Material and Methods: ES nanofiber mats were prepared by electrospinning. New Zealand white rabbits underwent surgical transection of the Achilles tendon and repair by: (a) SR: standard Kessler suture þ epitendinous suture (5-0 vicryl). (b) ES/PTB: a single stay suture and a section of ES mat, stained with 0.1% Rose Bengal (RB), wrapped around the tendon and bonded with 532 nm light (0.3 W/cm 2 , 125 J/cm 2). (c) SR þ ES/PTB: a combination of (a) and (b). Gross appearance, extent of adhesion formation and biomechanical properties of the repaired tendon were evaluated at Days 7, 14, or 28 post-operatively (n ¼ 8 per group at each time point). Results: Ultimate stress (US) and Young's modulus (E) in the SR group were not significantly different from the ES/PTB group at Days 7

Research paper thumbnail of Epidermal Growth Factor (EGF) Ligand Release by Substrate-specific A Disintegrin and Metalloproteases (ADAMs) Involves Different Protein Kinase C (PKC) Isoenzymes Depending on the Stimulus

Journal of Biological Chemistry, 2011

Research paper thumbnail of Tissue Engineering: Controlling Spatial Organization of Multiple Cell Types in Defined 3D Geometries (Adv. Mater. 41/2012)

Advanced Materials, 2012

ABSTRACT

Research paper thumbnail of Controlling Spatial Organization of Multiple Cell Types in Defined 3D Geometries

Research paper thumbnail of Spatially Controlled 3D Printing of Dual‐Curing Urethane Elastomers

Advanced Materials Technologies

Research paper thumbnail of Macromolecular gelatin properties affect fibrin microarchitecture and tumor spheroid behavior in fibrin-gelatin gels

Research paper thumbnail of Designer, injectable gels to prevent transplanted Schwann cell loss during spinal cord injury therapy

Science Advances

Transplantation of patient-derived Schwann cells is a promising regenerative medicine therapy for... more Transplantation of patient-derived Schwann cells is a promising regenerative medicine therapy for spinal cord injuries; however, therapeutic efficacy is compromised by inefficient cell delivery. We present a materials-based strategy that addresses three common causes of transplanted cell death: (i) membrane damage during injection, (ii) cell leakage from the injection site, and (iii) apoptosis due to loss of endogenous matrix. Using protein engineering and peptide-based assembly, we designed injectable hydrogels with modular cell-adhesive and mechanical properties. In a cervical contusion model, our hydrogel matrix resulted in a greater than 700% improvement in successful Schwann cell transplantation. The combination therapy of cells and gel significantly improved the spatial distribution of transplanted cells within the endogenous tissue. A reduction in cystic cavitation and neuronal loss were also observed with substantial increases in forelimb strength and coordination. Using an ...

Research paper thumbnail of Comparative Molecular Analysis of Cancer Behavior Cultured In Vitro, In Vivo, and Ex Vivo

Cancers

Current pre-clinical models of cancer fail to recapitulate the cancer cell behavior in primary tu... more Current pre-clinical models of cancer fail to recapitulate the cancer cell behavior in primary tumors primarily because of the lack of a deeper understanding of the effects that the microenvironment has on cancer cell phenotype. Transcriptomic profiling of 4T1 murine mammary carcinoma cells from 2D and 3D cultures, subcutaneous or orthotopic allografts (from immunocompetent or immunodeficient mice), as well as ex vivo tumoroids, revealed differences in molecular signatures including altered expression of genes involved in cell cycle progression, cell signaling and extracellular matrix remodeling. The 3D culture platforms had more in vivo-like transcriptional profiles than 2D cultures. In vivo tumors had more cells undergoing epithelial-to-mesenchymal transition (EMT) while in vitro cultures had cells residing primarily in an epithelial or mesenchymal state. Ex vivo tumoroids incorporated aspects of in vivo and in vitro culturing, retaining higher abundance of cells undergoing EMT wh...

Research paper thumbnail of Quantitative criteria to benchmark new and existing bio-inks for cell compatibility

Research paper thumbnail of 3D Bioprinting: Dual-Stage Crosslinking of a Gel-Phase Bioink Improves Cell Viability and Homogeneity for 3D Bioprinting (Adv. Healthcare Mater. 19/2016)

Advanced Healthcare Materials, 2016

Research paper thumbnail of Dual-Stage Crosslinking of a Gel-Phase Bioink Improves Cell Viability and Homogeneity for 3D Bioprinting

Advanced healthcare materials, 2016

Current bioinks for cell-based 3D bioprinting are not suitable for technology scale-up due to the... more Current bioinks for cell-based 3D bioprinting are not suitable for technology scale-up due to the challenges of cell sedimentation, cell membrane damage, and cell dehydration. A novel bioink hydrogel is presented with dual-stage crosslinking specifically designed to overcome these three major hurdles. This bioink enables the direct patterning of highly viable, multicell type constructs with long-term spatial fidelity.

Research paper thumbnail of A photoactivated nanofiber graft material for augmented Achilles tendon repair

Lasers in Surgery and Medicine, 2012

Background and Objective: Suture repair of Achilles tendon rupture can cause infection, inflammat... more Background and Objective: Suture repair of Achilles tendon rupture can cause infection, inflammation and scarring, while prolonged immobilization promotes adhesions to surrounding tissues and joint stiffness. Early mobilization can reduce complications provided the repair is strong enough to resist re-rupture. We have developed a biocompatible, photoactivated tendon wrap from electrospun silk (ES) to provide additional strength to the repair that could permit early mobilization, and act as a barrier to adhesion formation. Study Design/Material and Methods: ES nanofiber mats were prepared by electrospinning. New Zealand white rabbits underwent surgical transection of the Achilles tendon and repair by: (a) SR: standard Kessler suture þ epitendinous suture (5-0 vicryl). (b) ES/PTB: a single stay suture and a section of ES mat, stained with 0.1% Rose Bengal (RB), wrapped around the tendon and bonded with 532 nm light (0.3 W/cm 2 , 125 J/cm 2). (c) SR þ ES/PTB: a combination of (a) and (b). Gross appearance, extent of adhesion formation and biomechanical properties of the repaired tendon were evaluated at Days 7, 14, or 28 post-operatively (n ¼ 8 per group at each time point). Results: Ultimate stress (US) and Young's modulus (E) in the SR group were not significantly different from the ES/PTB group at Days 7

Research paper thumbnail of Epidermal Growth Factor (EGF) Ligand Release by Substrate-specific A Disintegrin and Metalloproteases (ADAMs) Involves Different Protein Kinase C (PKC) Isoenzymes Depending on the Stimulus

Journal of Biological Chemistry, 2011

Research paper thumbnail of Tissue Engineering: Controlling Spatial Organization of Multiple Cell Types in Defined 3D Geometries (Adv. Mater. 41/2012)

Advanced Materials, 2012

ABSTRACT

Research paper thumbnail of Controlling Spatial Organization of Multiple Cell Types in Defined 3D Geometries

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