Multi-Scale Flow and Shock Wave Research Laboratory, USTC

Graduate Research Assistant

• Designed and calibrated the laser scattering device for measuring the droplet size in a large-scale, outdoor atomization field
• Investigated near and far fields of atomization under the condition of axismmetrical dissemination and breakup of liquid with/without constraints

Rensselaer Polytechnic Institute

Associate Professor

• Teach courses: Biomechanics, Cell Biomechanics
• Research in Cell Chirality, Stem Cell Mechanobiology, and Tissue Engineering

Rensselaer Polytechnic Institute

Assistant Professor

• Teach courses: Biomechanics, Cell Biomechanics
• Research in Cell Chirality, Stem Cell Mechanobiology, and Tissue Engineering

Laboratory for Stem Cells and Tissue Engineering, Columbia University

Postdoc

• Investigated cell chirality for implications in left-right asymmetry in development
• Studied the pattern of stem cell differentiation in a multi-cellular form with micro-contact printing, micro-fluidic technique, and soft lithography
• Explored mechanical control of the distribution of stem cell function inside 3D microstructures
• Performed research in functional tissue engineering of bone, cartilage, and heart with stem cells novel biomaterial, and advanced bioreactors

Orthopedic Research Lab, Department of Orthopedic Surgery, Columbia University

Graduate Research Assistant

• Determined contents of water and proteoglycans inside articular cartilage with magnetic resonance imaging (MRI) for osteoarthritis detection at early stages

the Liu Ping Laboratory for Functional Tissue Engineering Research, Columbia University

Graduate Research Assistant

• Developed an experimental/theoretical strategy to quantify both nonlinear mechanical properties and biochemical compositions of the cartilage by simple unconfined compression tests
• Simplified the Triphasic mixture theory and obtained analytic solutions for physical events of biological tissues under mechanical loading
• Built a mathematic model for residual stress and curling behaviors of articular cartilage and successfully validated with experiments
• Proposed a linear viscoelastic model for hydrogel-based tissue engineered constructs to directly calculate their intrinsic mechanical properties
• Investigated the response of chondrocytes to mineral contents for developing long-lasting bone-cartilage interface

High-Throughput Cell Aggregate Culture for Stem Cell Chondrogenesis

Methods in Molecular Biology

High-Throughput Cell Aggregate Culture for Stem Cell Chondrogenesis

Methods in Molecular Biology

Astrocytes Increase ATP Exocytosis Mediated Calcium Signaling in Response to Microgroove Structures

Scientific Reports

Following central nervous system (CNS) injury, activated astrocytes form glial scars, which inhibit axonal regeneration, leading to long-term functional deficits. Engineered nanoscale scaffolds guide cell growth and enhance regeneration within models of spinal cord injury. However, the effects of micro-/nanosize scaffolds on astrocyte function are not well characterized. In this study, a high throughput (HTP) microscale platform was developed to study astrocyte cell behavior on micropatterned surfaces containing 1 μm spacing grooves with a depth of 250 or 500 nm. Significant changes in cell and nuclear elongation and alignment on patterned surfaces were observed, compared to on flat surfaces. The cytoskeleton components (particularly actin filaments and focal adhesions) and nucleus-centrosome axis were aligned along the grooved direction as well. More interestingly, astrocytes on micropatterned surfaces showed enhanced mitochondrial activity with lysosomes localized at the lamellipodia of the cells, accompanied by enhanced adenosine triphosphate (ATP) release and calcium activities. These data indicate that the lysosome-mediated ATP exocytosis and calcium signaling may play an important role in astrocytic responses to substrate topology. These new findings have furthered our understanding of the biomechanical regulation of astrocyte cell–substrate interactions, and may benefit the optimization of scaffold design for CNS healing.

High-Throughput Cell Aggregate Culture for Stem Cell Chondrogenesis

Methods in Molecular Biology

Astrocytes Increase ATP Exocytosis Mediated Calcium Signaling in Response to Microgroove Structures

Scientific Reports

Following central nervous system (CNS) injury, activated astrocytes form glial scars, which inhibit axonal regeneration, leading to long-term functional deficits. Engineered nanoscale scaffolds guide cell growth and enhance regeneration within models of spinal cord injury. However, the effects of micro-/nanosize scaffolds on astrocyte function are not well characterized. In this study, a high throughput (HTP) microscale platform was developed to study astrocyte cell behavior on micropatterned surfaces containing 1 μm spacing grooves with a depth of 250 or 500 nm. Significant changes in cell and nuclear elongation and alignment on patterned surfaces were observed, compared to on flat surfaces. The cytoskeleton components (particularly actin filaments and focal adhesions) and nucleus-centrosome axis were aligned along the grooved direction as well. More interestingly, astrocytes on micropatterned surfaces showed enhanced mitochondrial activity with lysosomes localized at the lamellipodia of the cells, accompanied by enhanced adenosine triphosphate (ATP) release and calcium activities. These data indicate that the lysosome-mediated ATP exocytosis and calcium signaling may play an important role in astrocytic responses to substrate topology. These new findings have furthered our understanding of the biomechanical regulation of astrocyte cell–substrate interactions, and may benefit the optimization of scaffold design for CNS healing.

Sequential gelation of tyramine-substituted hyaluronic acid hydrogels enhances mechanical integrity and cell viability

Medical & Biological Engineering & Computing

Tyramine-substituted hyaluronic acid (HA–Tyr) hydrogels formed by the oxidative coupling reaction of hydrogen peroxide (H2O2) and horseradish peroxidase (HRP) have been used for cellular encapsulation and protein delivery. Crosslinking density and gelation time can be tuned by altering the H2O2 and HRP concentrations. Previous studies using HA–Tyr constructs report significant mechanical degradation after 21 days of culture. In this work, exogenous supplementation of HRP after initial gelation resulted in superior mechanical properties in acellular hydrogels and improved viability and proliferation in cell-laden constructs. Swelling of the acellular hydrogels was prevented in the samples receiving exogenous HRP. Monolayer studies showed no negative effect of relevant HRP concentrations on the viability of human adipose-derived stem cells (hASCs) and improved the viability of hASCs cultured with HRP and H2O2 compared to H2O2 alone. Taken together, this study demonstrates that HA–Tyr hydrogel properties could be modified by exogenous supplementation of HRP to tune scaffold degradation and improve cell viability by mitigating the negative effects of oxidative stress.

High-Throughput Cell Aggregate Culture for Stem Cell Chondrogenesis

Methods in Molecular Biology

Astrocytes Increase ATP Exocytosis Mediated Calcium Signaling in Response to Microgroove Structures

Scientific Reports

Following central nervous system (CNS) injury, activated astrocytes form glial scars, which inhibit axonal regeneration, leading to long-term functional deficits. Engineered nanoscale scaffolds guide cell growth and enhance regeneration within models of spinal cord injury. However, the effects of micro-/nanosize scaffolds on astrocyte function are not well characterized. In this study, a high throughput (HTP) microscale platform was developed to study astrocyte cell behavior on micropatterned surfaces containing 1 μm spacing grooves with a depth of 250 or 500 nm. Significant changes in cell and nuclear elongation and alignment on patterned surfaces were observed, compared to on flat surfaces. The cytoskeleton components (particularly actin filaments and focal adhesions) and nucleus-centrosome axis were aligned along the grooved direction as well. More interestingly, astrocytes on micropatterned surfaces showed enhanced mitochondrial activity with lysosomes localized at the lamellipodia of the cells, accompanied by enhanced adenosine triphosphate (ATP) release and calcium activities. These data indicate that the lysosome-mediated ATP exocytosis and calcium signaling may play an important role in astrocytic responses to substrate topology. These new findings have furthered our understanding of the biomechanical regulation of astrocyte cell–substrate interactions, and may benefit the optimization of scaffold design for CNS healing.

Sequential gelation of tyramine-substituted hyaluronic acid hydrogels enhances mechanical integrity and cell viability

Medical & Biological Engineering & Computing

Tyramine-substituted hyaluronic acid (HA–Tyr) hydrogels formed by the oxidative coupling reaction of hydrogen peroxide (H2O2) and horseradish peroxidase (HRP) have been used for cellular encapsulation and protein delivery. Crosslinking density and gelation time can be tuned by altering the H2O2 and HRP concentrations. Previous studies using HA–Tyr constructs report significant mechanical degradation after 21 days of culture. In this work, exogenous supplementation of HRP after initial gelation resulted in superior mechanical properties in acellular hydrogels and improved viability and proliferation in cell-laden constructs. Swelling of the acellular hydrogels was prevented in the samples receiving exogenous HRP. Monolayer studies showed no negative effect of relevant HRP concentrations on the viability of human adipose-derived stem cells (hASCs) and improved the viability of hASCs cultured with HRP and H2O2 compared to H2O2 alone. Taken together, this study demonstrates that HA–Tyr hydrogel properties could be modified by exogenous supplementation of HRP to tune scaffold degradation and improve cell viability by mitigating the negative effects of oxidative stress.

Geometry and Force Control of Cell Function

Journal of Cellular Biochemistry