# Development of a sample preparation protocol for 3D kidney ultrastructural analysis and immunolabeling by light microscopy

> **NIH NIH R43** · PANLUMINATE INC. · 2023 · $274,419

## Abstract

Abstract
The success of cohort studies such as the NIDDK Kidney Precision Medicine Project (KPMP)
with its massive amount of samples depends on the cost and time-efficient evaluation of kidney
biopsies at multiple scales. Assessing the structure of kidney tissue at the nanoscale (~10
nm) and evaluating the 3-D distribution of protein biomarkers in that context is, however,
currently severely limited as it depends on expensive, time-consuming and extremely
complex correlative light and electron microscopy (CLEM) as the only suitable tool. Panluminate
has developed a proprietary new tissue expansion technology we call pan-Expansion
Microscopy (pan-ExM), that directly addresses this challenge. By combining ~25-fold linear
expansion of biological samples with novel bulk (pan) staining of amino acids, pan-ExM is
capable of mapping the 3-D nanoscale distribution of specific biomarkers in the context of
kidney ultrastructure. Hallmark ultrastructural features such as podocyte foot processes and
cristae in mitochondria can now be resolved by their characteristic pan-staining pattern,
analogous to heavy-metal stains in electron microscopy (EM). In contrast to EM/CLEM,
however, pan-ExM is an all-optical method that allows researchers to interrogate tissue samples
using standard confocal microscopes; this offers important advantages in terms of time, cost,
complexity and sample preservation versus EM alternatives. Our proposed Phase I project is to
develop and validate pan-ExM for kidney samples. Specifically we will: (1) optimize and validate
a new antibody-labeling pan-ExM protocol in freshly fixed kidney tissue; and (2) develop and
validate a novel ~25x tissue expansion protocol for archived FFPE kidney biopsies. This work is
designed to lay the foundation for a Phase II project that will establish pan-ExM as a robust and
powerful imaging technology in the kidney field by enabling every researcher in nephrology to
locate multiple specific protein biomarkers within their 3D contextual compartments at the ~10
nm scale. Our long-term ambition is for pan-ExM to become a core imaging technology for
kidney tissue atlases as well as a preferred technique for targeted research and diagnostic
applications, thereby paving the road to precision medicine for nephrology.

## Key facts

- **NIH application ID:** 10760947
- **Project number:** 1R43DK137685-01
- **Recipient organization:** PANLUMINATE INC.
- **Principal Investigator:** Ons M'Saad
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $274,419
- **Award type:** 1
- **Project period:** 2023-09-15 → 2024-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10760947

## Citation

> US National Institutes of Health, RePORTER application 10760947, Development of a sample preparation protocol for 3D kidney ultrastructural analysis and immunolabeling by light microscopy (1R43DK137685-01). Retrieved via AI Analytics 2026-05-26 from https://api.ai-analytics.org/grant/nih/10760947. Licensed CC0.

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