Group Projects

Patient-Specific 3D Microfluidic Tissue Model for Multiple Myeloma

Multiple myeloma (MM), an incurable B cell malignancy, is the second most common heme malignancy in the U.S. with a survival time of 3 to 4 years. This disease is characterized by monoclonal proliferation of malignant plasma cells in the bone marrow (BM), the presence of high levels of monoclonal serum antibody, and the development of osteolytic bone lesions. Unfortunately, progress in understanding and treating the disease has been significantly limited by the fact that primary human MM tumor cells have been difficult to survive and propagate ex vivo. The difficulty is due to the lack of an in vitro technology capable of reproducing the complex bone marrow microenvironments surrounded by bone tissues.

In collaboration with Dr. Jenny Zilberberg and Dr. David Siegel, MD, at Hackensack University Medical Center, we are exploring a new approach to emulate the bone marrow microenvironments in vitro and therefore to culture primary human multiple MM cells. The system uses a three-dimensional (3D) ossified tissue to mimic the tumor niche and particularly to recapitulate adhesive interactions between MM cells and osteoblasts residing at the tissue interface between bone and bone marrow, i.e., endosteum. We have found that the reconstructed endosteum niche allows the primary MM cells to survive and expand several times during a few weeks of culture.

Our approach offers significant paradigm-changing opportunities to study the biological mechanisms responsible for drug resistance and relapse with this incurable disease, as well as provide a platform on which pharmaceutical and biotechnology companies can develop new efficacious drugs. Furthermore, the platform may provide a potential clinical assessment tool that will assist physicians to prescribe personalized treatment regimens with existing drugs tailored for individual MM patients. Based on this breakthrough discovery, our research team is: (1) conducting proof of concept studies to demonstrate the clinical utility of our ex vivo MM cell culturing technology and (2) studying other tissues and cancer models to expand the potential broad commercial applicability of the platform technology. This research is supported by the Stevens Center for Bioinnovation and the John Theurer Cancer Center at Hackensack University Medical Center.

Microfluidic Reconstruction of 3D Osteocytic Cellular Networks

The goal of this research is to develop an in vitro microfluidic culture device that can be used to reproduce the mechanotransduction function of osteocytes, residing in native cortical bone tissues. As master regulators of homeostatic bone remodeling, osteocytes embedded are known to sense local compressive strain and initiate strain-dependant new bone formation by osteoblasts with sclerostin as one of major signaling molecules. Despite of this important understanding, there is currently no in vitro model that is capable of reproducing the physiological phenotype and mechanotransduction function of primary osteocytes for routine use in biomedical research and preclinical drug evaluation.

We hypothesize that microbeads can be used to guide the re-establishment of 3D cellular networks of primary osteocytes harvested from animals and humans during microfluidic perfusion culture. The microbeads are being engineered to mimic, upon their close packed assembly with osteocytes in the microfluidic culture chamber, the geometry and mechanical support function of the extracellular matrix of bones. The microfluidic culture device is also used to: (1) apply compressive cycling loading to 3D osteocyte networks reconstructed in the culture chamber and (2) reproduce the strain-sclerostin relationship observed by in vivo studies.

For anticipated impact, comparison to in vivo data will scientifically validate the use of our 3D tissue model, as a novel means of studying fundamental biological mechanisms associated with osteocytes as master regulators of bone remodeling. Also, the comparison will provide new significant insight for follow-on development to culture primary human osteocytes and extend the microfluidic device's capability for simulating human bone remodeling that includes osteocyte-regulated bone formation and bone resorption. We envision that such a microfluidic human 3D bone tissue model may ultimately replace animal testing in preclinical evaluation of authentic human tissue response to drugs, for example, sclerostin antibodies that are being pursued to treat 10 million osteoporosis patients and bone metastases with 350,000 deaths per year in the U.S. This research is sponsored by the National Institutes of Health, and is conducted in collaboration with Prof. Antonio Valdevit at Stevens and Dr. Jenny Zilberberg at Hackensack University Medical Center.

Inkjet-Printed Drug-Eluting Micropatterns for Infection Prevention and Wound Healing

While our ability to produce orthopaedic implants has tremendously improved over past several decades, hospital-acquired bacterial infection during implantation procedures has emerged as the dominant mode of implant failure. Infection occurs because a small number of bacteria adhere preferentially to implant surfaces and form biofilms, which protect the bacteria from host defense and antibiotics. Consequently, infected implants must be surgically removed with tremendous patient trauma and additional healthcare burden of over $3B in the U.S. every year. Despite the severity of this public health problem, progress has been limited due to the lack of our understanding of the complex interplay among host tissues, bacteria, and biomaterials. This research is aimed at generating a new scientific base for designing new implant surfaces by establishing a highly cross-disciplinary research frontier that cuts across biomaterials, device infection, and microfluidics.

The goal of this project is to explore the possibility of creating drug-eluting, bioresorbable micropatterns that can be used to promote bone tissue formation and prevent biofilm formation on orthopaedic implant surfaces. The first major objective of the project is to develop an inkjet-based evaporative assembly method for printing micropatterns with tailorable nanocomposite morphology for controlled drug release. The second major objective is to project the ability of micropatterns to kill bacteria and prevent biofilm colony formation while enhancing 3D bone tissue-like structure formation. The key methodology is to use a microfluidic 3D bone tissue model, which has been developed to overcome tremendous ambiguity associated with using conventional in vitro biofilm assays and host cell culture experiments, to evaluate the efficacy of infection-preventing biomaterials.

To date, we have demonstrated: (1) the drug-eluting function of inkjet-printed micropatterns with antibiotic and biphasic calcium phosphate (BCP) nanoparticles dispersed in a bioresorbable poly(d,l-lactic-co-glycolic) acid matrix; (2) the micropatterns? efficacy in immediately and completely killing bacteria upon inoculation while enhancing the calcified extracellular matrix production of osteoblasts; and (3) the ability of chitosan as an alternative matrix material to increase the mobility and phagocytosis of macrophages, as another important function that the micropattern matrix can provide to prevent biomaterials-associated bacterial infection. We have also shown that the 3D bone tissue model?s potential in: (1) significantly reducing the number of biomaterial samples and culture experiments required to assess in vitro efficacy for wound-healing and infection prevention and (2) in situ monitoring of dynamic interactions of biomaterials with bacteria as wells as with tissue cells simultaneously. This research is sponsored by the Biomaterials program of the National Science Foundation, and is conducted in collaboration with Prof. Hongjun Wang at Stevens.

Graphene-Based, Printed Flexible Supercapacitors

Supercapacitors utilize electrostatic charge separation at electrode-electrolyte interfaces as an energy storage mechanism. This mechanism avoids battery-related faradic chemical reactions, dimensional changes, solid-state diffusion between electrodes and electrolytes, and consequently provides fast charge/discharge rates in seconds while being able to withstand millions of charge/discharge cycles. Because of these attractive functions, supercapacitors can be used, for example, to complement batteries in smart phones to provide instant battery power back in seconds as well as increase battery life.

We recently invented the inkjet printing and thermal reduction of graphene oxide nanosheets, as a new means of fabricating graphene electrodes for printed flexible supercapacitors. Graphene is an ideal material for flexible supercapacitor electrodes because of its unique set of interesting properties: (1) mechanically strong and yet very conformal and flexible like if one can envision a nanoscale silk scarf, (2) electrochemically stable, (3) electrically conductive, and (4) affordable as it can be produced from graphite powder mined from earth. Also, it can be assembled during inkjet printing to generate very high surface area and optimum nanoscale porosity.

Our current effort is aimed at: (1) further improving the performance of printed graphene electrodes through graphene modifications, (2) prototyping truly flexible supercapacitors with "roll-to-roll" compatible materials and packaging, and (3) integrating with printed electronics for demonstrating rapid power charging and boosting functions in wireless mobile device applications. For near-term impact, we are addressing the rapidly growing $0.5B supercapacitor market for mobile electronic devices in collaboration with our government and industrial collaborators.

Stevens Lab