# Stem cell therapy for fracture nonunion under inflammatory diseases

> **NIH NIH R21** · WASHINGTON UNIVERSITY · 2020 · $207,902

## Abstract

ABSTRACT
Fracture nonunion poses a significant clinical problem. In the United States, approximately 1.6 million bone
fractures encounter prolonged healing or non-union each year. Fracture nonunion treatment usually involves
complicated and massive procedures in practice, and sometimes needs multiple surgeries, therefore increases
the cost of health care and results in marked patient disability. The major population bearing with these clinical
complications are patients with inflammatory conditions, e.g, elder patients, smoking, diabetic or rheumatoid
arthritis (RA) patients, highlighting the potential deleterious role of chronic systemic inflammation in fracture
r epair.
 The overarching hypothesis of this proposal is that under inflammatory conditions, Dnmt3b
overexpression on stem cells can be achieved in an auto-regulated and feedback-controlled manner and
therefore leads to restoration of stem cell differentiation in cell cultures and fracture repair in RA mice. This
hypothesis is supported by our preliminary data wherein we show that Dnmt3b is highly expressed in fracture
callus during fracture repair and Dnmt3b is the major DNA methyltransferase (Dnmt) responsive to cytokines in
MPCs. Relevant to our proposal, we provide evidence that 1) inflammation decreases Dnmt3b expression in
MPCs in vivo and in vitro and leads to fracture nonunion; 2) inflammatory signals inhibit Dnmt3b in an NF-κB-
dependent manner; and 3) Dnmt3b gain-of-function (GOF) in MPCs shows protective effect from inflammation
in vitro and accelerates fracture repair in mice. We therefore propose to further engineer feedback-controlled
anti-inflammatory stem cells with Dnmt3b overexpression, making the cells have the capacity to tune
inflammation and meanwhile overcome DNA methylation alterations.
 CRISPR/Cas9 genome editing platform will be used to generate self-regulated anti-inflammatory stem
cells and examine its effect against inflammation on stem cell differentiation in vitro and in vivo in the context
with fracture repair. Two main Specific Aims are proposed. Specific Aim 1 will establish the effect of Dnmt3b
overexpression on restoration of DNA methylation and stem cell differentiation under inflammation in vitro.
Specific Aim 2 will establish the protective effect of self-regulated stem cells on fracture nonunion against
inflammation in vivo. This work will define Dnmt3b as a novel target to treat fracture nonunion. The customized
therapeutic stem cells will open innovative possibilities for more effective treatments to fracture nonunion
especially under inflammatory diseases.

## Key facts

- **NIH application ID:** 9957927
- **Project number:** 1R21AR077226-01
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Farshid Guilak
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $207,902
- **Award type:** 1
- **Project period:** 2020-08-01 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9957927

## Citation

> US National Institutes of Health, RePORTER application 9957927, Stem cell therapy for fracture nonunion under inflammatory diseases (1R21AR077226-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/9957927. Licensed CC0.

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