Application of Progenitor Niche Signals to Ex Vivo Nephrogenesis

Key Personnel

Leif Oxburgh (PI)
Maine Medical Center

Thomas Carroll (PI)
University of Texas Southwestern
Ondine Cleaver (PI)
University of Texas Southwestern
David Kaplan (PI)
Tufts University

Project Description

In this multi-PI project we aim to understand how the three major cell types of the developing kidney can be integrated on a scaffold to reproduce key features of the kidney. Summaries of the 4 focus areas within the project are provided below. These lines of investigation are being pursued in parallel, with the 4 participating laboratories acting as a single integrated research group with the unified goal of developing engraftable laboratory-grown kidney tissue.

At the 56 minute mark of this video of Dr. Francis Collins' testimony for the Senate Health Committee, he refers to the Regenerative Medicine Innovation Project (RMIP) supplement to this project and work being done in kidney regeneration.

Focus on: Stromal Biology

**PI:** Thomas Carroll
*University of Texas Southwestern*

Key Personnel: Alicia Fessler, Ashwani Kumar Gupta, Harini Ramalingam

Optimal kidney functions require complex patterning of both the nephrons and blood vessels. We study how the distinct interstitial microenvironments that exist within the embryonic and adult kidney affect the development and function of this organ. Our ultimate goal is to define the stromal signals that promote the growth of 3-D, physiologically responsive nephrons with integrated vasculature in biological scaffolds.

Focus on: Vascular Biology

**PI:** Ondine Cleaver
*University of Texas Southwestern*

Key Personnel: Edward Daniel

Nascent blood vessels develop in a coordinated manner with kidney nephrons. We aim to establish a molecular signature for endothelial cells (ECs) in the developing kidney, from nephron stem cell generation to nephron tubule differentiation, throughout embryonic development and into adulthood. Preliminary observations reveal distinct heterogeneity in EC gene expression in the developing kidney; however its functional impact is unknown. We will define when and where blood vessels appear during nephron formation, distinguishing vasculogenic versus angiogenic events. We will test necessity and sufficiency of endothelial signals on nephron progenitor self-renewal versus differentiation. We will also determine whether specific, regionally expressed factors play functional roles in either helping to sustain progenitors or trigger NPC expansion versus differentiation.

Focus on: Biomaterials

Key Personnel: Shreyas Jadhav, Sophia Szymkowiak

We focus on the design and study of 3D scaffolds to support kidney cell and tissue needs. Silk protein scaffolds provide our framework due to the versatility and utility towards cell and tissue goals, including porous features for transport, tunable mechanical properties, support for long term tissue growth, controlled/slow degradation and an absence of cell-specific epitopes for signaling. We will use silk biomaterial scaffold systems to provide structure and, with the addition of appropriate ECM components, signaling cues for nephrogenesis via cells from our project collaborators (Leif, Tom, Ondine). The goal is to utilize these scaffolds to engineer modular, compartmentalized systems that support and guide nephron progenitor cell (NPC) maintenance and differentiation, and cellular signaling between stromal cells, cells of the vasculature, and NPCs.

Focus on: Nephron Progenitor Biology

**PI:** Leif Oxburgh
*Maine Medical Center*

Key Personnel: Prasenjit Sarkar

We study the population dynamics of the nephron progenitor cell population with the aim of identifying the sub-populations that are best suited to new tissue formation. This in-depth study of the micro anatomy of the nephron progenitor cell niche involves understanding proliferation, adhesion, and signaling properties of the various nephron progenitor sub populations, defining their growth properties on biological scaffolds, and characterizing the influence of stromal and vascular cells on them.