Methods and systems for determining spatial patterns of biological targets in a sample
The present disclosure provides methods and assay systems for use in spatially encoded biological assays, including assays to determine a spatial pattern of abundance, expression, and/or activity of one or more biological targets across multiple sites in a sample. In particular, the biological targets comprise proteins, and the methods and assay systems do not depend on imaging techniques for the spatial information of the targets. The present disclosure provides methods and assay systems capable of high levels of multiplexing where reagents are provided to a biological sample in order to address tag the sites to which reagents are delivered; instrumentation capable of controlled delivery of reagents; and a decoding scheme providing a readout that is digital in nature.
1. A method for determining the presence and/or location of a genomic DNA molecule in a biological sample, the method comprising:
(a) attaching the biological sample affixed to a support to a first microfluidic device having multiple first addressing channels, wherein a first addressing channel identifies a first area in the biological sample;
(b) delivering a first probe through the first addressing channel to the first area in the biological sample, wherein the first probe comprises (i) a first ligation region, (ii) a first address tag that identifies the first area in the biological sample, and (iii) a second ligation region;
(c) attaching the biological sample affixed to the support to a second microfluidic device having multiple second addressing channels, wherein a second addressing channel identifies a second area in the biological sample that intersects with the first area; and
(d) delivering a second probe through the second addressing channel to the second area in the biological sample, wherein the second probe comprises: (i) a second address tag that identifies the second area in the biological sample and (ii) a third ligation region, wherein the second probe is coupled to the first probe through ligation between the second ligation region and the third ligation region at an intersection between the first area and the second area, thereby generating a ligation product, and the first and second address tags are used to identify the presence and/or the location of the genomic DNA molecule at the intersection in the biological sample.
2. The method of claim 1 , wherein the multiple first addressing channels are substantially parallel to each other and the multiple second addressing channels are substantially parallel to each other.
3. The method of claim 1 , wherein the multiple first addressing channels and/or the multiple second addressing channels is n addressing channels, wherein n is an integer between 20 and 1000.
4. The method of claim 3 , wherein n is about 50.
5. The method of claim 1 , wherein the width of each of the multiple first addressing channels and/or each of the multiple second addressing channels is about 1 micrometers (μm) to about 500 μm.
6. The method of claim 1 , wherein the depth of each of the multiple first addressing channels and/or each of the multiple second addressing channels is about 1 μm to about 500 μm.
7. The method of claim 1 , wherein the distance between each of the multiple first addressing channels and/or between each of the multiple second addressing channels is about 1 μm to about 2.0 millimeters (mm).
8. The method of claim 1 , wherein the second area forms an angle with the first area at the intersection, and wherein the angle is about 10 degrees to about 90 degrees.
9. The method of claim 8 , wherein the angle is about 90 degrees.
10. The method of claim 1 , further comprising attaching adaptors to each end of the genomic DNA molecule, wherein at least one of the adaptors comprises a fourth ligation region.
11. The method of claim 10 , wherein the first probe is coupled to the genomic DNA molecule through ligation between the first ligation region and the fourth ligation region.
12. The method of claim 11 , further comprising extending the first probe using the genomic DNA molecule as a template.
13. The method of claim 1 , wherein the second probe is coupled with the third probe by extension followed by ligation.
14. The method of claim 10 , wherein the first probe is coupled to one of the adaptors through ligation between the first ligation region and the fourth ligation region.
15. The method of claim 1 , wherein the first probe further comprises a variable tag region, a primer sequence, a sequencing adaptor, a biotin moiety, or a combination thereof.
16. The method of claim 1 , wherein the second probe further comprises a variable tag region, a primer sequence, a sequencing adaptor, a biotin moiety, or a combination thereof.
17. The method of claim 1 , wherein the third probe further comprises a variable tag region, a sequencing adaptor, or a combination thereof.
18. The method of claim 1 , wherein the first probe, the second probe, and/or the third probe comprises DNA.
19. The method of claim 1 , wherein the genomic DNA molecule in the biological sample comprises accessible genomic DNA.
20. The method of claim 1 , further comprising amplifying the ligation product.
21. The method of claim 20 , wherein the amplifying is performed by polymerase chain reaction.
22. The method of claim 1 , wherein the method further comprises determining the sequence of the first and second address tags by nucleic acid sequencing or high-throughput sequencing.
23. The method of claim 1 , further comprising, prior to step (a), staining the biological sample using immunohistochemistry or immunofluorescence.
24. The method of claim 23 , further comprising imaging the biological sample.
25. The method of claim 1 , further comprising imaging the biological sample.
26. The method of claim 1 , wherein the method determines the presence and location of the genomic DNA molecule in the biological sample.
27. The method of claim 1 , wherein the biological sample is a fixed tissue sample, a fresh frozen tissue sample, an embedded tissue sample, or a processed tissue sample.
28. The method of claim 27 , wherein the fixed tissue sample is a formalin-fixed, paraffin-embedded (FFPE) sample.
29. The method of claim 1 , further comprising determining the presence and/or location of additional genomic DNA molecules in the biological sample, wherein the one or more additional genomic DNA molecules is an integer between 1,000 and 100,000.