About

Alexander Groisman is a professor whose research focuses on the development and application of new devices and techniques based on micro-flows and soft materials for cell biology and protein folding research. His work involves collaboration with many bio-research laboratories in the San Diego area and outside, with particular interests including chemotaxis, gradient response, microbial cultures in microchambers, and the migration of blood cells. His research aims to advance understanding of cellular and protein dynamics through innovative microfluidic and soft matter technologies, contributing to the broader field of biological physics by exploring how physical principles can be harnessed to elucidate biological processes at the cellular and molecular levels.

Research topics

• Biology
• Cell biology
• Biophysics
• Chemistry
• Computer Science
• Genetics
• Physics
• Biochemistry
• Mechanics
• Materials science

Selected publications

• CellBoost: A pipeline for machine assisted annotation in neuroanatomy

  AI Open · 2024-01-01 · 2 citations

  articleOpen access

  One of the important yet labor intensive tasks in neuroanatomy is the identification of select populations of cells. Current high-throughput techniques enable marking cells with histochemical fluorescent molecules as well as through the genetic expression of fluorescent proteins. Modern scanning microscopes allow high resolution multi-channel imaging of the mechanically or optically sectioned brain with thousands of marked cells per square millimeter. Manual identification of all marked cells is prohibitively time consuming. At the same time, simple segmentation algorithms suffer from high error rates and sensitivity to variation in fluorescent intensity and spatial distribution. We present a methodology that combines human judgement and machine learning that serves to significantly reduce the labor of the anatomist while improving the consistency of the annotation. As a demonstration, we analyzed murine brains with marked premotor neurons in the brainstem. We compared the error rate of our method to the disagreement rate among human anatomists. This comparison shows that our method can reduce the time to annotate by as much as ten-fold without significantly increasing the rate of errors. We show that our method achieves significant reduction in labor while achieving an accuracy that is similar to the level of agreement between different anatomists.

  PublisherDOI

• Different Cell Migration Modes: Insights from Traction Force Microscopy and Modeling

  Biophysical Journal · 2021-02-01

  articleOpen access
  PublisherOA PDFDOI

• Elastic wrinkling of keratocyte lamellipodia driven by myosin-induced contractile stress

  Biophysical Journal · 2021 · 13 citations

  • Cell biology
  • Biophysics
  • Chemistry
  PublisherOA PDFDOI

• Integrin-based mechanosensing through conformational deformation

  Biophysical Journal · 2021 · 44 citations

  • Biophysics
  • Chemistry
  • Cell biology
  PublisherOA PDFDOI

• Cell Mechanics at the Rear Act to Steer the Direction of Cell Migration

  Cell Systems · 2020 · 46 citations

  • Computer Science
  • Cell biology
  • Mechanics
  PublisherOA PDFDOI

• Modeling cell turning by mechanics at the cell rear

  bioRxiv (Cold Spring Harbor Laboratory) · 2020-06-04 · 2 citations

  preprintOpen access

  Abstract In this study, we explore a simulation of a mechanical model of the keratocyte lamellipodium as previously tested and calibrated for straight steady-state motility [1] and for the process of polarization and motility initiation [2]. In brief, this model uses the balance of three essential forces (myosin contraction, adhesive drag and actin network viscosity) to determine the cell’s mechanical behavior. Cell shape is set by the balance between the actin polymerization-driven protrusion at the cell boundary and myosin-driven retraction of the actin-myosin network. In the model, myosin acts to generate contractile stress applied to a viscous actin network with viscous resistance to actin flow created by adhesion to the substrate. Previous study [3] demonstrated that similar simple model with uniform constant adhesion predicts a rotating behavior of the cell; however, this behavior is idealized, and does not mimic observed features of the keratocyte’s turning behavior. Our goal is to explore what are the consequences of introducing mechanosensitive adhesions to the model.

  PublisherDOI

• Porous Materials: Neuroprotective Effect of Nerve Growth Factor Loaded in Porous Silicon Nanostructures in an Alzheimer's Disease Model and Potential Delivery to the Brain (Small 45/2019)

  Small · 2019-11-01 · 2 citations

  articleOpen access

  In article number 1904203, Ester Segal, Orit Shefi, and co-workers safely implant or biolistically introduce degradable porous silicon carriers into the brains of mice for continuous and effective release of nerve growth factor, a neuroprotective drug for Alzheimer's disease.

  PublisherOA PDFDOI

• Neuroprotective Effect of Nerve Growth Factor Loaded in Porous Silicon Nanostructures in an Alzheimer's Disease Model and Potential Delivery to the Brain

  Small · 2019-09-04 · 32 citations

  article

  Abstract Nerve growth factor (NGF) plays a vital role in reducing the loss of cholinergic neurons in Alzheimer's disease (AD). However, its delivery to the brain remains a challenge. Herein, NGF is loaded into degradable oxidized porous silicon (PSiO 2 ) carriers, which are designed to carry and continuously release the protein over a 1 month period. The released NGF exhibits a substantial neuroprotective effect in differentiated rat pheochromocytoma PC12 cells against amyloid‐beta (Aβ)‐induced cytotoxicity, which is associated with Alzheimer's disease. Next, two potential localized administration routes of the porous carriers into murine brain are investigated: implantation of PSiO 2 chips above the dura mater, and biolistic bombardment of PSiO 2 microparticles through an opening in the skull using a pneumatic gene gun. The PSiO 2 ‐implanted mice are monitored for a period of 8 weeks and no inflammation or adverse effects are observed. Subsequently, a successful biolistic delivery of these highly porous microparticles into a live‐mouse brain is demonstrated for the first time. The bombarded microparticles are observed to penetrate the brain and reach a depth of 150 µm. These results pave the way for using degradable PSiO 2 carriers as potential localized delivery systems for NGF to the brain.

  PublisherDOI

• Author Correction: Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks

  Nature · 2018-07-04 · 1 citations

  erratumOpen access
  PublisherOA PDFDOI

• Hyperexpandable, self-healing macromolecular crystals with integrated polymer networks

  Nature · 2018-04-24 · 181 citations

  articleOpen access
  PublisherOA PDFDOI

Recent grants

• Collaborative Research: Characterization of a BIoluminescence Reporter System for Mechanical Stress

  NSF · $252k · 2013–2016

Frequent coauthors

• Victor Steinberg

  Harbin Engineering University

  9 shared

• Edgar Gutierrez

  University of California, San Diego

  9 shared

• Julie A. Theriot

  Howard Hughes Medical Institute

  6 shared

• Maria K. Pospieszalska

  La Jolla Institute for Immunology

  5 shared

• Klaus Ley

  5 shared

• Prithu Sundd

  Medical College of Wisconsin

  5 shared

• Terence Hwa

  5 shared

• Greg M. Allen

  University of California, San Francisco

  4 shared

Labs

• UCSD Biological PhysicsPI