Isolation, storage, and delivery of extracellular vesicles using asymmetric depth filters
Asymmetric depth filtration for isolation of EVs or other desired nanoparticles from a biological or other fluid with high yield and purity in a simple, cost-effective manner. Such a method includes passing the biological fluid through the asymmetric depth filter (e.g., in a single pass) where the fluid is introduced into the filter at an entry portion, where components of the biological fluid pass through the wider entry portion of the pores before advancing towards the narrower exit portion of the pores, wherein EVs in the fluid become reversibly entrapped within the wider portion of the pores, while similarly sized soft, low-density lipids and/or proteins are pushed more deeply into the filter, so that the reversibly entrapped EVs can be released by simply reversing the flow, while the similarly sized soft low-density lipids and/or proteins remain permanently entrapped within the pores of the filter.
1. A method of isolating extracellular vesicles or nanoparticles from a fluid using an asymmetric depth filter, the method comprising:
(a) providing a fluid including extracellular vesicles or nanoparticles;
(b) providing an asymmetric depth filter, wherein the asymmetric depth filter has asymmetric pores where the asymmetric pores have a first width at an entry portion of the asymmetric depth filter and have a second width at an exit portion of the asymmetric depth filter, wherein the first width is greater than the second width; and
(c) passing the fluid through the asymmetric depth filter in a forward direction, wherein the fluid is introduced into the asymmetric depth filter at the entry portion, so that components of the fluid pass through the entry portion of the asymmetric pores before advancing towards the exit portion of the asymmetric pores, wherein extracellular vesicles or nanoparticles become reversibly entrapped within the entry portion of the asymmetric pores, and any proteins or low-density lipids, the proteins and low-density lipids being similarly sized to the size of the extracellular vesicles or nanoparticles are trapped in the asymmetric depth filter;
(d) rinsing at least a portion of the extracellular vesicles or nanoparticles reversibly entrapped within the entry portion of the asymmetric pores with a rinsing material, wherein rinsing with the rinsing material increases a purity of extracellular vesicles or nanoparticles that are recovered with a flow reversal across the asymmetric depth filter, after such rinsing.
2. The method of claim 1 , wherein the asymmetric pores are tortuous.
3. The method of claim 1 , wherein the rinsing material is flowed through the asymmetric depth filter in the forward direction, from an entry surface to an exit surface.
4. The method of claim 1 , wherein the similarly sized low-density lipids or proteins comprise at least one of a low density lipoprotein, a very-low density lipoprotein, or protein agglomerates.
5. The method of claim 1 , wherein passing the fluid through the asymmetric depth filter is facilitated through centrifugation.
6. The method of claim 5 , wherein a driving force associated with such centrifugation is less than 1000×g.
7. The method of claim 1 , wherein the asymmetric depth filter comprises at least one of cellulose acetate, regenerated cellulose, polyether sulfone, or aramid.
8. The method of claim 1 , the method further comprising, before step (c), preparing the fluid by removing at least a portion of nanoparticles larger than desired nanoparticles from the fluid.
9. The method of claim 8 , wherein such preparation includes one or more of centrifugation or conventional filtration through a filter media having pores having a size through which the extracellular vesicles or nanoparticles pass, and extracellular vesicles or nanoparticles larger than a desired size do not pass through the pores.
10. The method of claim 1 , wherein the fluid comprises a biological fluid.
11. The method of claim 1 , wherein the fluid comprises extracellular vesicles.
12. The method of claim 1 , the method further comprising, after step (c), subjecting the asymmetric depth filter to a flow reversal, by passing a carrier fluid through the asymmetric depth filter along a reverse flow pathway, entering the asymmetric pores from the exit portion, and exiting the asymmetric pores at the entry portion, such reverse flow releasing the reversibly entrapped extracellular vesicles or nanoparticles from the asymmetric depth filter.
13. The method of claim 1 , wherein the rising material comprises a buffer.
14. A method of isolating extracellular vesicles from a biological fluid using an asymmetric depth filter, the method comprising:
(a) providing a biological fluid including extracellular vesicles;
(b) providing an asymmetric depth filter, wherein the asymmetric depth filter has asymmetric pores where the asymmetric pores have a first width at an entry portion of the asymmetric depth filter and have a second width at an exit portion of the asymmetric depth filter, wherein the first width is greater than the second width;
(c) passing the biological fluid through the asymmetric depth filter in a forward direction, wherein the biological fluid is introduced into the asymmetric depth filter at the entry portion, so that components of the biological fluid pass through the entry portion of the asymmetric pores before advancing towards the exit portion of the asymmetric pores, wherein extracellular vesicles become reversibly entrapped within the entry portion of the asymmetric pores; and
(d) rinsing at least a portion of the extracellular vesicles reversibly entrapped withing the entry portion of the asymmetric pores with a rising material, wherein the rising material increases a purity of extracellular vesicles that are recovered with a flow reversal across the asymmetric depth filter, after such rinsing.
15. A method of isolating extracellular vesicles from a biological fluid using an asymmetric depth filter, the method comprising:
(a) providing a biological fluid including extracellular vesicles;
(b) providing an asymmetric depth filter, wherein the asymmetric depth filter has asymmetric pores where the asymmetric pores have a first width at an entry portion of the asymmetric depth filter and have a second width at an exit portion of the asymmetric depth filter, wherein the first width is greater than the second width; and
(c) passing the biological fluid through the asymmetric depth filter in a forward direction, wherein the biological fluid is introduced into the asymmetric depth filter at the entry portion, so that components of the biological fluid pass through the entry portion of the asymmetric pores before advancing towards the exit portion of the asymmetric pores, wherein extracellular vesicles become reversibly entrapped within the entry portion of the asymmetric pores;
(d) subjecting the asymmetric depth filter to a flow reversal, by passing a carrier fluid through the asymmetric depth filter along a reverse flow pathway, entering the asymmetric pores from the exit portion, and exiting the asymmetric pores at the entry portion, such reverse flow releasing the reversibly entrapped extracellular vesicles from the asymmetric depth filter.
16. The method of claim 15 , further comprising rinsing at least a portion of the extracellular vesicles reversibly entrapped within the entry portion of the asymmetric pores with a rinsing material, wherein rinsing with the rinsing material increases a purity of extracellular vesicles that are recovered with a flow reversal across the asymmetric depth filter, after such rinsing.