Extracellular Vesicles for Gaining Insights into Tissue Senescent Signatures: A SenNET Pilot and Exploratory Project

Abstract This Administrative Supplement to KAPP-Sen Tissue Mapping Center (TMC) award (U54AG075941) funded by National Institute of Aging to leverage recent advances in the development of technologies used for the detection of senescence markers within tissue-specific extracellular vesicles (EVs). The PA-20-272 (Administrative Supplements to Existing NIH Grants and Cooperative Agreements) notes that this funding mechanism be used to cover cost increases that are associated with achieving certain new research objectives, as long as the research objectives are within the original scope of the peer-reviewed and approved project. Specific Aims of U54AG075941 include Aim 1: Coordinate research activities across KAPP-Sen TMC Collaborative sites in support of Sen-Net goals towards mapping cellular senescence and its associated secretory phenotype in the healthy human kidney, adipose tissues, pancreas and placenta. Aim 2: Obtain tissues from healthy kidney transplant donors (kidneys, fat, skin), C-section pregnancies (placenta, cord, fat, skin), outpatient healthy donor biopsies (fat, skin), beating heart brain dead donors (full pancreas) and IIPD/Prodo (dispersed pancreas). Aim 3: Generate highest-quality data pertaining to cellular senescence including scRNA- Seq, snRNA-Seq, spatial transcriptomics, immunohistochemistry and Telomere-associated DDR foci (TAFs) in all tissues. Aim 4: Perform high-level integrative data analysis required for the creation of aUases of human cellular senescence in collaboration with other TMCs, CODDC and NIH staff. Our Administrative Supplement proposal seeks to leverage ongoing work conducted by our KAPP- Sen TMC to create maps of senescent cells in Kidneys, Adipose tissues, Pancreas, and Placenta with advances involving new techniques designed to isolate, identify, characterize, and quantify tissue-specific EVs from blood and urine, combined with senescent biomarkers. Our Overarching Hypothesis raises the rather intriguing possibility that EV subsets and their protein cargo components may function as a liquid biopsy, thus permitting the non-invasive qualitative and quantitative evaluation of the senescent cell burden residing within the tissues from which those EVs likely originate. Furthermore, suppose future evidence was to support this postulate. In that case, such a development might permit clinicians to one day link peripheral blood- or urine- borne EV biomarker data to information residing in curated high-resolution senescent cell data obtained via SenNET.