Our research applies engineering approaches to develop therapeutic strategies that promote regeneration of healthy central nervous system tissues. A common theme across many central nervous system disorders, including spinal cord injury and cancer, is significant alterations to the extracellular matrix, such as changes in biochemical composition and structural mechanics of the tissue. A lack of understanding of how the extracellular matrix is fundamentally altered by injury or disease, and thus how these changes can be reversed to restore normal function, has been a major limitation to the development of new treatments. This gap in understanding is due to a shortage of tools available for investigating the unique extracellular environment in the central nervous system and its relationship to cell function. Thus, it is crucial to develop new platform tools in which to study these interactions and identify new clinical strategies. To address this need, my lab is developing biomimetic, hydrogel-based microenvironments with modular features that can be tuned to 1) quantify independent effects of various extracellular parameters on cell function and 2) provide a means for precise external control over cell function. Furthermore, we are developing methods for high-throughput monitoring of transcription factor activity in live cells cultured within these same biomaterial platforms. Acquisition of dynamic, high-throughput data from cells cultured in physiologically relevant conditions will provide key mechanistic insights into the progression of nervous system pathologies and, ultimately, identify new target pathways for regenerative therapies.

News

Research

Spinal Cord Injury Repair

A major focus of our lab is the repair of spinal cord injury (SCI), for which there are no treatments available that can achieve regeneration. Development of clinically effective strategies to restore function after SCI will require consideration of multiple aspects of this inhibitory environment. Ultimately, we aim to develop a combinatorial therapy that addresses multiple barriers to spinal cord repair by incorporating substrate-immobilized biochemical cues, genetically encoded regulatory factors, and cell replacement.

Injectable Biomaterials to Engineering the Neural Microenvironment

Hydrogel biomaterials are a clinically promising strategy for spinal cord repair because they can be designed to be injected and formed directly in the lesion, approximate mechanical and biochemical properties of the healthy spinal cord and finally as a medium to deliver regenerative factors. Our lab focuses on a combination of poly(ethylene) glycol (PEG) and hyaluronic acid (HA) precursors using aqueous chemistries that allow for in situ crosslinking of hydrogels and gentle encapsulation of biological agents and cells. HA is a linear-chain polysaccharide that has been shown to significantly augment wound healing, nerve regeneration, cell migration and is a principle extracellular matrix component in the central nervous system.  HA-PEG hydrogels will be employed as a platform from which to modularly add various environmental components (e.g., extracellular matrix-derived adhesion sites, biodegradable crosslinks and mechanical properties).  Using this modular platform, we have the unique opportunity to evaluate the individual and combinatorial effects of various aspects of the in vivo microenvironment on spinal cord regeneration in a mouse model.

Biomaterial-Mediated Gene Therapy

Delivery of lentiviral vectors from biomaterials is a powerful tool to influence the in vivo microenvironment. Lentiviral vectors enable sustained, localized protein expression and facile delivery of virtually any factor and combinations of factors simply by encapsulation of viral particles within hydrogels. This project aims to engineer HA-PEG-based hydrogel microenvironments that support delivery of lentiviral vectors encoding for neurotrophic factors and to evaluate their effects on regeneration in a mouse model of SCI. We are investigating delivery of lentiviral vectors encoding for factors that address multiple barriers to spinal cord repair, including axon survival and regeneration, glial scar formation, excessive and chronic inflammation and myelination.

Biomaterial Carriers for Neural Stem/Progenitor Cell Transplantation

SCI causes extensive death of oligodendrocytes, whose neurotrophic support and myelin wrapping of axons are vital to functional connectivity in the spinal cord. As mature oligodendrocytes cannot self-renew, insufficient quantity of oligodendrocytes is a significant barrier to recovery. Therapeutic delivery of neural stem/progenitor cells (NPCs) to replace lost oligodendrocytes has shown promise to treat SCI and other neurodegenerative conditions; however, low survival rates and inefficient differentiation after transplantation have been major limitations. In addition, despite reports of positive effects of stem cell transplants on SCI repair, differentiation and integration into host tissue are not observed on a scale adequate to achieve functional repair. To address these issue, we aim to design hydrogel constructs as vehicles for efficient, localized delivery of NPCs that will provide a microenvironment designed to shield transplanted cells from the host inflammatory response, actively promote NPC differentiation into oligodendrocytes and enhance functional myelination of host axons.

High-throughput, Dynamic Arrays to Quantify Intracellular Signaling

This array technique is based on a library of lentiviral reporters of transcription factor activation that drive expression of luciferase. Extracellular cues initiate complex intracellular signaling cascades that terminate in translocation of multiple transcription factors to the nucleus to directly modulate gene expression. Bioluminescence imaging is then performed in live, 3D cultures to quantitatively monitor transcription factor activation in real-time, which represents the current "functional state" of a cell and ultimately drives differentiation.

Dynamic Measurements of Intracellular Signaling Pathways during Oligodendrocyte Differentiation

A major factor contributing to the failure of stem cell therapies for SCI is an inhibition of oligodendrocyte differentiation by the local, in vivo microenvironment. As the process of oligodendrocyte differentiation is not well understood, there is a need to identify the microenvironmental parameters required to direct oligodendrocyte differentiation. To date, a handful of protocols describing differentiation of human oligodedendrocytes in vitro have been reported. However, there is little consistency among the different methods and terminally differentiated yields of oligodendrocytes. Moreover, none of these methods has been effective, simple or consistent enough to be adopted by the field as a standard protocol. In order to effectively employ cell-based therapies for axon remyelination, it is imperative to gain a better fundamental understanding of the mechanisms that drive human oligodendrogenesis. To this end, our lab is employing arrays of transcription factor activity to identify common set(s) of master transcription factors that are uniquely activated in human neural stem/progenitor as they undergo differentiation in real-time. Once characterized, strategies to induce simultaneously activation of this core set of transcription factors can be developed to substantially increase researchers’ abilities to efficiently and directly generate oligodendrocytes. Moreover, this core set of transcription factors can be experimentally monitored to identify extrinsic parameters that further drive differentiation.

Identification of Novel Drug Targets for Treatment of Glioblastoma Multiforme

Gliobastoma multiforme is an extremely aggressive cancer that is typically unresponsive to currently available pharmacological agents. The ultimate goal of these studies is to identify key differences in the extracellular environment surrounding glioblastomas that impart drug resistance with the goal of exploiting these differences to develop novel, more effective pharmaceutical agents. Using our transcription factor reporter library, we are screening for intracellular pathways that are differentially activated in response to varying microenvironmental cues, as presented by 3D hydrogels. Furthermore, we are quantifying the real-time, dynamic changes in transcription factor activity as glioblastoma cells acquire resistance to alkylating agents and tyrosine kinase inhibitors. Acquisition of systems biology level data will provide key insights into the early, conserved events that initiate this resistance. Moreover, characterization of key transcriptional pathways that confer apoptotic resistance will identify promising new targets for adjunct therapies aimed at rendering glioblastomas sensitive to chemotherapeutic agents. This project is in collaboration with Dr. David Nathanson, Assistant Professor in Medical and Molecular Pharmacology at UCLA.

Biomaterial Microenvironments that Mimic Healthy and Diseased States of the Central Nervous System

The extracellular environment has significant, but largely uncharacterized, involvement in function of the central nervous system. Biomaterials can be engineered to present defined microenvironments that can greatly simplify the experimental variability in biological systems so that effects of a single variable can be experimentally isolated in vitro. In addition, through systematic manipulation of different microenvironmental features presented by the biomaterial, we can identify which aspects of a cell's surroundings instrumentally contribute to specific pathologies and apply this knowledge to develop new clinical therapies that act by locally altering the extracellular environment. In particular, we aim to use biomaterial tools to identify key physiological interactions between cells and their environment during central nervous system tissue development, repair, and disease progression. Identification of crucial alterations in these interactions will lead to impactful mechanistic discoveries and ultimately new clinical strategies based on controlled manipulation of these interactions.

Biomaterial Constructs to Characterize the Role of Extracellular Matrix in Glioblastoma Multiforme

There is a large body of evidence that suggests that the unique extracellular environment in the brain, which contains few fibrous proteins and high amounts of hyaluronic acid, is responsible for the characteristic aggressiveness and resistance to conventional treatments observed in brain tumors categorized as glioblastoma mulitforme. However the specific interactions between tumor cells and the extracellular matrix and their relationship to tumor physiology are largely unknown. In general, these mechanisms have been challenging to elucidate, in part because of the lack of physiologically translatable models that can be studied in vitro. Thus, we are developing hyaluronic acid-based hydrogels as ex vivo culture systems that can be tuned to mimic the native microenvironment in healthy and glioblastoma-affected brain. HA and its cell surface receptors are dramatically upregulated in the microenvironment of glioblastoma and this shift likely has a substantial contributes to the increased the migratory capacity and resistance to chemotherapeutic drugs. Furthermore, glioblastoma cells cultured within 3D environments, and particularly those containing hyaluronic acid, more closely mirror the in vivo tumor physiology than when cells are cultured using standard techniques. Notably, the biochemical and biophysical landscape presented to encapsulated cells can be precisely and independently controlled to enable investigations of the quantitative effects of these features on cell physiology so that clinically relevant data can be acquired in an ex vivo setting. Our research aims to 1) fully characterize the extracellular matrix in tissues isolated from clinical glioblastomas and 2) optimize microenvironmental features presented by hydrogels to best recapitulate the in vivo tumor niche in 3D cultures of patient-derived glioblastoma cells. This project is in collaboration with Dr. David Nathanson, Assistant Professor in Medical and Molecular Pharmacology at UCLA.

Development of Biomaterial Systems that Drive Oligodendrocyte Differentiation

Because of our limited understanding of the highly complex cell-cell and cell-matrix interactions in the central nervous system and how these interactions coordinate tissue function, it has been necessary to use intensive in vivo animal models almost exclusively. Thus, new clinical treatments have been slow to appear. As the in vivo behavior of neural stem/progenitor cells often deviates greatly from that observed in vitro using traditional methods, our research aims to develop ex vivo culture environments that mimic the geometrical, mechanical and chemical features of the native extracellular matrix to facilitate basic and translational neuroscience research. The ability to finely tune the presentation of these cues within a modular platform will enable ex vivo investigation of cell-matrix interactions within conditions that approximate those in vivo so that physiologically relevant data can be obtained in a simplified context. Identification of essential cell-ECM interactions as therapeutic targets will be greatly facilitated by acquiring high-throughput data to screen for key interactions that mediate re-myelination by newly differentiated oligodendrocytes. Ultimately, we aim to translate these microenvironments in vivo as therapies that directly alter the inhibitory environment that develops with chronic inflammation in the central nervous system.

Publications

M. Skoumal, S.K. Seidlits, S. Shin, L.D. Shea. Localized lentivirus delivery via peptide interactions. (2016) Biotech. Bioeng., doi: 10.1002/bit.25961.

D.S. Hernandez, E.T. Ritschdorff, S.K. Seidlits, C.E. Schmidt, J.B. Shear. (2016) Functionalizing micro-3D-printed protein hydrogels for cell adhesion and patterning. J. Mater. Chem. B, doi: 10.1039/C5TB02070K.

D.A. McCreedy, D.J. Margul, S.K. Seidlits, R.M. Boehler, J. Antane, R. Thomas, D.R. Smith, T. He, T.V. Kukushliev, B. Vedia, J. Lamano, S.W. Goldsmith, G. Sissman, L.D. Shea. (2016) Semi-automated counting of axon regeneration in PLG spinal cord bridges. J. Neurosci. Methods, doi:10.1016/j.jneumeth.2016.01.021.

Z.Z. Khaing, S.K. Seidlits. (2015) Hyaluronic acid and neural stem cells: Implications for biomaterial design. J Mater Chem B, DOI: 10.1039/C5TB00974J.

Christopher M. Walthers, S.K. Seidlits. (2015) Gene delivery strategies for spinal cord repair, Biomarkers Insights, 10(Suppl 1):11-29.

S.K. Seidlits, K.A. Hlavaty, L.D. Shea. (2014) “DNA delivery for regeneration” in Biomaterials and Regenerative Medicine, ed. P.X. Ma. Cambridge University Press, Cambridge, MA.

A.M. Thomas*, S.K. Seidlits*, (co-first authors*), A.G. Goodman, T.V. Kukushliev, D.M. Hassani, B.J. Cummings, A.J. Anderson, L.D. Shea. (2014) Sonic hedgehog and neurotrophin-3 increase oligodendrocyte numbers and myelination after spinal cord injury. Integrative Biology. 6(7):694-705.

S.K. Seidlits, R.M. Gower, J.A. Shepard, L.D. Shea. (2013) Hydrogels for lentiviral gene delivery. Expert Opinion on Drug Delivery, 10(4):499-509.
A.M. Thomas, M.B. Kubilius, S.J. Holland, S.K. Seidlits, R.M. Boehler, A. J. Anderson, B.J. Cummings, L.D. Shea. (2013) Channel density and porosity of degradable bridging scaffolds on axon growth after spinal injury. Biomaterials 34(9):2213-2220.

Z.Z. Khaing, B.D. Milman, J.E. Vanscoy, S.K. Seidlits, R.J. Grill, C.E. Schmidt. (2011) High MW hyaluronic acid limits astrocyte proliferation and scar formation after SCI. J. Neural Eng. 8(4):046033.

S.K. Seidlits, C.T. Drinnan, R.R. Petersen, J.B. Shear, L.J. Suggs, C.E. Schmidt. (2011) Fibronectin-hyaluronic acid composites for three-dimensional endothelial cell culture. Acta Biomaterialia 7(6):2401-2409.

Y. Yang, S.K. Seidlits, M.M. Adams, Lynch VM, C.E. Schmidt, E.V. Ansyln, J.B. Shear. (2010) A highly selective low-background fluorescent imaging agent for nitric oxide. J. Am. Chem. Soc. 132(38):13114-13116.

S.K. Seidlits*, Z.Z. Khaing*, (co-first authors*) R.R. Petersen, J.D. Nickels, J.E. Vanscoy, J.B. Shear†, C.E. Schmidt† (co-corresponding authors). (2010) The effects of hyaluronic acid hydrogels with tunable mechanical properties on neural progenitor cell differentiation. Biomaterials 31:3930-3940.

S.K. Seidlits, C.E. Schmidt*, J.B. Shear* (co-corresponding authors*). (2009) High-resolution patterning of hydrogels in three dimensions using direct-write photofabrication for cell guidance. Adv. Funct. Mater. 19:3543-3551.

G. Kijanka, R. Barry, H. Chen, E. Gould, S.K. Seidlits, J. Schmid, M. Morgan, D.Y. Mason, J. Cordell, D. Murphy. (2009) Defining the molecular target of an antibody derived from nuclear extract of Jurkat cells using protein arrays. Anal. Biochem. 395(2):119-124.

S.K. Seidlits, J.Y. Lee, C.E. Schmidt. (2008) Nanostructured scaffolds for neural applications. Nanomedicine, 3(2):183-99.

S.K. Seidlits, N.A. Peppas. (2007) “Star polymers and dendrimers in nanotechnology and drug delivery” in Nanotechnology in Therapeutics: Current Technology and Applications, ed. Peppas, N.A., Hilt, J.Z., Thomas, J.B. Horizon Press, pp. 317-348.

F.K. Kasper, S.K. Seidlits, A. Tang, R.S. Crowther, D.H. Carney, M.A. Barry, A.G. Mikos. (2005) In vitro release of plasmid DNA from oligo(poly(ethylene glycol) fumarate) hydrogels. J Control. Release. 104(3):521-539.

S. Seidlits, T. Reza, K.A. Briand, A.B. Sereno. (2003) Voluntary spatial attention benefits voluntary not reflexive saccadic eye movements. TheScientificWorld Journal; 3:881-902.

People

Principal Investigator

stephanie seidlits compressed

Stephanie Seidlits, Ph.D., CV, seidlits@ucla.edu
Assistant Professor, Bioengineering, University of California, Los Angeles
M.S., Ph.D., University of Texas, Austin
B.S., Rice University

Research Areas: cell and tissue engineering, neural tissue engineering, spinal cord injury, glioblastoma multiforme, extracellular matrix, hyaluronic acid, biomaterials, hydrogels, signal transduction, lentiviral vectors, gene therapy

Post-Doctoral Researchers

Chris Walthers

Chris Walthers, Ph.D., walthers@ucla.edu
Ph.D., University of California, Los Angeles
B.S., University of North Carolina, Chapel Hill

Research Areas: oligodendrocyte differentiation, biomimetic hydrogels, transcription factor arrays, spinal cord injury

Ph.D. Student Researchers

arshia

Arshia Ehsanipour, aehsanip@ucla.edu
B.S., University of California, Davis
Research Areas: spinal cord injury, injectable hydrogels

Jesse-e1424145868995

Jesse Liang, jesse.liang92@gmail.com
B.S., University of California, Los Angeles
Research Areas: oligodendrocyte differentiation, biomimetic hydrogels

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Alireza Sohrabi, asohrabi@ucla.edu
M.S., University of Twente
B.S., Amirkabir University of Technology, Tehran Polytechnic
Research Areas: biomimetic hydrogels, hyaluronic acid

Weikun

Weikun Xiao, weikun.xiao@ucla.edu
B.S., University of Illinois, Urbana-Champagne
Research Areas: glioblastoma multiforme, hyaluronic acid hydrogels, transcription factor arrays

Undergraduate Student Researchers

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Tasha Aboufadel

Aishani

Aishani Ataliwala

phillipcox

Phillip Cox

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Peipei Lyu

IMG_6190

Robel Dagnew

IMG_6195

Jaimie Mayner

IMG_6182

Catherina (Songping) Sun

IMG_6186

Julius Yee

IMG_6180

Rongyu Zhang

Tiffany Kyu
Alexis Morrison Litke
Nadia Mortezagholi
Armando Puente
Sara Rashidi
Ryan Stoutamore
Joseph Tseng
Meagan Yuen

Past Lab Members

Maggie Morysewicz (M.S.)

Contact

Department of Bioengineering
University of California, Los Angeles
Engineering V, 5121 H
Los Angeles, CA 91401
Office phone: 310-267-5244
Email: seidlits@ucla.edu