Elasticity and mechanical metamaterials
Does DMSO soften or stiffen cell membranes?
Open access · cc by · source: Europe PMC
DMSO's effect on membranes depends on their composition and phase: it strongly alters cholesterol-free bilayers, barely touches cholesterol-rich ones, and makes red cells leak ATP even at low doses.
Study at a glance
- Design
- Animal / in-vitro — In vitro biophysics: FTIR on multilamellar vesicles, flicker spectroscopy of giant vesicles and of single human red blood cells before/after DMSO, plus a luminescence ATP-release assay.
- N
- No single N; at least 100 vesicles screened per condition for morphology, several red cells per sample for flicker analysis, and ATP measured five times per DMSO concentration.
- Population
- Synthetic POPC/sphingomyelin bilayers with and without cholesterol, and red blood cells from healthy donors aged 20-30
- Outcome
- Main transition temperature, probe-based free volume, bending modulus, and extracellular ATP release
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
In the two-lipid membrane DMSO raised the melting transition from 27°C to 33°C, reduced the free volume in the membrane core and made vesicles floppy with excess area, but had no measurable effect on bending rigidity; the cholesterol-rich membrane showed no change in transition or free volume but appeared to stiffen. In red cells, 1% DMSO raised the bending modulus by about 37%, 5% softened the membrane, and 10% had only a weak, transient effect. DMSO triggered significant ATP release from red cells at concentrations as low as 3%, plateauing around 5%.
Methodology
The authors made model membranes from a two-lipid mix and from the same mix with a large amount of cholesterol, and exposed them to DMSO, a common cryoprotectant. They used infrared spectroscopy to track melting transitions and a buried probe molecule to gauge free volume, and filmed the thermal flickering of giant vesicles to extract bending rigidity. They also filmed the same red blood cells before and up to 90 minutes after adding 1, 5 or 10% DMSO, and measured ATP released from red cells.
Limitations
Stable giant vesicles could not be formed above 5% DMSO, so model membranes were not tested at the 10% used for cryopreservation. The stiffening of the cholesterol-rich vesicles is described as apparent and unexplained, and the spread of values in that system was large. The mechanism of ATP release (regulated transport versus membrane damage) was not identified, and red-cell results come from a small number of young healthy donors without reported cell counts.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
The same chemical can stiffen, soften or do nothing depending on the membrane and the dose.
Additives change membrane mechanics in a composition-dependent way: in vitro, DMSO left the bending rigidity of cholesterol-free POPC/sphingomyelin vesicles unchanged while shifting their melting transition, whereas in red blood cells 1% DMSO raised the bending modulus by about 37% and 5% softened the membrane.
Evidence for the claim as stated.
Cholesterol's stiffening effect is clear for phase-separated ordered domains, but DMSO results show that adding cholesterol-rich composition does not always translate into predictable mechanical responses to perturbation; the systems, techniques (X-ray fitting versus flicker spectroscopy) and lipid mixtures differ, so absolute rigidity values are not directly comparable.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
Cholesterol's stiffening effect is clear for phase-separated ordered domains, but DMSO results show that adding cholesterol-rich composition does not always translate into predictable mechanical responses to perturbation; the systems, techniques (X-ray fitting versus flicker spectroscopy) and lipid mixtures differ, so absolute rigidity values are not directly comparable.
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