Methods for determining a location of an analyte in a biological sample
Provided herein are methods of determining a location of a target analyte in a non-permeabilized biological sample that include the use of a blocking probe.
1. A method for reducing capture of a target nucleic acid in an area of an array not covered by a biological sample, the method comprising:
(a) disposing a biological sample onto an array at a first area, wherein the array comprises a plurality of capture probes and the biological sample is a non-permeabilized biological sample, wherein:
the first area comprises a capture probe of the plurality of capture probes comprising (i) a spatial barcode and (ii) a capture domain; and
a second area of the array comprises a capture probe of the plurality of capture probes comprising (i) a spatial barcode and (ii) a capture domain, and the second area is an area of the array not covered by the biological sample disposed on the array;
(b) contacting the second area of the array with a solution comprising a blocking probe, wherein the blocking probe comprises a nucleic acid sequence that binds to the capture domain of the capture probe in the second area of the array;
(c) removing residual solution comprising the blocking probe from at least the second area of the array prior to permeabilizing the biological sample; and
(d) permeabilizing the biological sample, such that the capture domain of the capture probe of the first area of the array binds to the target nucleic acid; thereby reducing capture of the target nucleic acid in the second area of the array not covered by the biological sample.
2. The method of claim 1 , wherein a 3′ end of the blocking probe is substantially complementary to about 5 to 100 nucleotides of the capture domain of the capture probe in the second area.
3. The method of claim 1 , wherein the blocking probe is a single-stranded blocking probe.
4. The method of claim 1 , wherein the blocking probe is a partially double-stranded blocking probe.
5. The method of claim 1 , wherein a 5′ end of the blocking probe is phosphorylated.
6. The method of claim 1 , wherein step (b) further comprises ligating the 5′ end of the blocking probe to a 3′ end of the capture probe in the second area of the array.
7. The method of claim 1 , wherein a 3′ end of the blocking probe comprises a chemical block.
8. The method of claim 7 , wherein the chemical block is an azidomethyl group.
9. The method of claim 1 , wherein the blocking probe comprises a hairpin structure.
10. The method of claim 1 , wherein the blocking probe comprises a locked nucleic acid.
11. The method of claim 1 , wherein the method further comprises, prior to step (a) or between steps (a) and (b), fixing and/or staining the biological sample.
12. The method of claim 11 , wherein the step of fixing the biological sample comprises the use of a fixative selected from the group consisting of: ethanol, methanol, acetone, formaldehyde, paraformaldehyde-Triton, glutaraldehyde, and combinations thereof.
13. The method of claim 11 , wherein the step of staining the biological sample comprises:
the use of a biological stain selected from the group consisting of: acridine orange, Bismarck brown, carmine, coomassie blue, cresyl violet, DAPI, eosin, ethidium bromide, acid fuchsine, hematoxylin, Hoechst stains, iodine, methyl green, methylene blue, neutral red, Nile blue, Nile red, osmium tetroxide, propidium iodide, rhodamine, safranin, and combinations thereof; or
the use of a detectable label selected from the group consisting of: a radioisotope, a fluorophore, a chemiluminescent compound, a bioluminescent compound, and combinations thereof.
14. The method of claim 1 , wherein the biological sample is selected from the group consisting of: a tissue sample, a fresh-frozen tissue section, a fixed tissue section, an organoid, embryonic stem cells, pluripotent stem cells, diseased cells, fetal cells, immune cells, cellular macromolecules, organelles, extracellular polynucleotides, and combinations thereof.
15. The method of claim 1 , wherein the biological sample is a clinical sample selected from the group consisting of: whole blood, blood-derived products, blood cells, cultured tissue, cultured cells, a cell suspension, and combinations thereof.
16. The method of claim 1 , wherein the removing in step (c) comprises washing.
17. The method of claim 1 , wherein the target nucleic acid is genomic DNA.
18. The method of claim 1 , wherein the target nucleic acid is RNA.
19. The method of claim 18 , wherein the RNA is mRNA.
20. A composition, comprising an array having a first area, wherein the array comprises a plurality of capture probes, wherein:
the first area comprises a capture probe of the plurality of capture probes comprising (i) a spatial barcode and (ii) a capture domain bound to a target nucleic acid from a biological sample, wherein the biological sample was previously disposed on the first area; and
a second area of the array comprises a capture probe of the plurality of capture probes comprising (i) a spatial barcode and (ii) a capture domain bound to a blocking probe, and the second area was not previously covered by the biological sample.
21. The composition of claim 20 , wherein a 3′ end of the blocking probe is substantially complementary to about 5 to 100 nucleotides of the capture domain of the capture probe in the second area.
22. The composition of claim 20 , wherein the blocking probe is ligated to a 3′ end of the capture probe in the second area.
23. The composition of claim 20 , wherein the array comprises one or more features, optionally wherein the one or more features comprises a bead.
24. A composition, comprising an array having a first area, wherein the array comprises a plurality of capture probes, wherein:
the first area comprises a capture probe of the plurality of capture probes comprising (i) a spatial barcode and (ii) a capture domain bound to a target nucleic acid from a biological sample, wherein the biological sample is disposed on the first area; and
a second area of the array comprises a capture probe of the plurality of capture probes comprising (i) a spatial barcode and (ii) a capture domain bound to a blocking probe, and the second area is not covered by the biological sample.
25. The composition of claim 24 , wherein a 3′ end of the blocking probe is substantially complementary to about 5 to 100 nucleotides of the capture domain of the capture probe in the second area.
26. The composition of claim 24 , wherein the blocking probe is ligated to a 3′ end of the capture probe in the second area.
27. The composition of claim 24 , wherein the array comprises one or more features, optionally wherein the one or more features comprises a bead.
28. The method of claim 1 , wherein the method further comprises:
(e) determining (i) a sequence corresponding to the spatial barcode of the capture probe of the first area of the array, or a complement thereof, and (ii) all or a portion of a sequence corresponding to the target nucleic acid, or a complement thereof, and using the sequences of (i) and (ii) to determine the location of the target nucleic acid in the biological sample.
29. The method of claim 28 , wherein the determining in step (e) comprises sequencing (i) the spatial barcode of the capture probe of the first area of the array, or a complement thereof, and (ii) all or a portion of the target nucleic acid, or a complement thereof.
30. The method of claim 28 , wherein the determining in step (e) comprises extending a 3′ end of the capture probe of the first area of the array using the target nucleic acid as a template.