# Single-cell measurement of cyclic stress on sickle blood cells by imaging-microfluidics

> **NIH NIH R01** · MASSACHUSETTS INSTITUTE OF TECHNOLOGY · 2021 · $635,308

## Abstract

Vaso-occlusive crises (VOC) are ultimately responsible for the majority of morbidity and mortality in sickle cell
disease (SCD). The initiation of VOC is not fully understood. For RBCs with sickle hemoglobin (HbS),
deoxygenation induces polymerization, reducing cellular mechanical deformability, among other biophysical
changes, and increasing VOC risk. By utilizing a recently developed interferometric phase and amplitude
microscopy (iPAM) technique, we found a subpopulation of “unfit” RBCs in the blood of SCD patients with altered
material properties including shape and viscosity. In a parallel study using a novel microfluidic assay for sickling
kinetics (MASK), we found that cellular defects appear to accumulate after either repeated sickling or mechanical
stress cycles, resulting in faster sickling, reduced deformability, and significant shape changes in sickle cells.
These observations suggest an overarching hypothesis that mechanical fatigue of sickle RBCs by repeated
sickling or mechanical loading in circulation causes “defects” to accumulate, producing an “unfit” subpopulation
of RBCs that is responsible for VOC initiation. This subpopulation of “unfit” RBCs can be distinguished by iPAM.
This proposal will examine this hypothesis by designing a next-generation iPAM platform integrated with MASK,
elucidating how repeated mechanical stress affects sickle RBC properties and influences VOC propensity. We
have assembled a team of investigators with relevant expertise to tackle this problem. These include Dr. So who
is an expert in bioimaging, Dr. Dao who is an expert in microfluidics and biomechanics, and Dr. Higgins who is
an expert in sickle cell disease pathophysiology. This team of investigators has worked together for over five
years with several joint publications. The work in this proposal is divided into four aims. Aim 1 focuses on
developing an extinction-based iPAM that will allow quantification of sickle RBC rheology in addition to fitness
index. The RBCs from sickle patients will be studied in a novel microfluidic platform that will enable amplitude-
modulated electrodeformation as well as repeated deoxygenation-oxygenation cycles for the cells under study.
These technological innovations will allow us to evaluate whether unfit RBCs are mechanically compromised
due to the accumulation of mechanical defects and whether these unfit cells sickle faster upon deoxygenation.
In Aim 2, we will add the ability to measure both oxy- and deoxy-Hb concentration in iPAM, allowing us to explore
whether mechanical cycling affects oxygen transport through the RBC membrane and its effect on HbS
polymerization. In Aim 3, polarization-resolved capability will be added to iPAM enabling us to detect whether
remnant polymerized HbS may persist inside unfit cells in the normoxic state acting as nuclei to promote
polymerization. We will evaluate this possibility as a complementary mechanism beside accumulated membrane
defects to explain why unfit cells may ...

## Key facts

- **NIH application ID:** 10235253
- **Project number:** 1R01HL158102-01
- **Recipient organization:** MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** Ming Dao
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $635,308
- **Award type:** 1
- **Project period:** 2021-05-01 → 2025-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10235253

## Citation

> US National Institutes of Health, RePORTER application 10235253, Single-cell measurement of cyclic stress on sickle blood cells by imaging-microfluidics (1R01HL158102-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10235253. Licensed CC0.

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