# Bioactive, "Self-fitting" Shape Memory Polymer (SMP) Scaffolds to Treat Cranial Bone Defects

> **NIH NIH R01** · TEXAS ENGINEERING EXPERIMENT STATION · 2020 · $488,792

## Abstract

ABSTRACT
 Our research goal is the development of a bioactive, “self-fitting” shape memory polymer (SMP)
scaffold to repair confined cranial defects by associated bone marrow-derived mesenchymal stem
cells (BMSCs). Autografts are associated with lengthy harvesting procedures, donor site morbidity as well as
difficulties in shaping and positioning the graft into the defect. Tissue engineering is a promising alternative but
requires a currently unmet need - a biomaterial scaffold which simultaneously provides: (1) the ability to
conformally fit into an irregular defect to enhance osseointegration, (2) bioactivity, (3) osteoinductivity
and (4) highly interconnected pores and controlled biodegradability necessary for cell migration, nutrient
diffusion and neotissue accumulation while avoiding brittle mechanical properties. The significance and
innovation of this approach is a new “self-fitting”, polydopamine-coated SMP scaffold design that achieves all
of these properties. Developed by the PI, the proposed hybrid SMP scaffolds are comprised of an organic
segment [poly(ε-caprolactone), PCL] and an inorganic silicon-containing segment [polydimethylsiloxane,
PDMS or poly(silyl ether), PSE]. The scaffold design meets key functional requirements: (1) Osseo-
integration: The SMP scaffold will be “self-fitting” as a result of its shape memory behavior, enabling
conformal fitting into an irregular defect by brief exposure to warm saline and locking of the new temporary
shape upon cooling to body temperature. (2) Bioactivity and (3) Osteoinductivity: A nanothick, bioactive
polydopamine coating will be applied to the SMP scaffold pore surfaces to support progenitor cell osteogenesis
as well the formation of hydroxyapatite necessary for osseointegration. (4) Interconnected Pores, Controlled
Biodegradability, and Robust Mechanical Properties: The SMP scaffold fabrication strategy enables high
porosities and pore interconnectivity while avoiding brittle mechanical behavior. The rate of scaffold
biodegradation will be controlled by inorganic segment type (i.e. PDMS or PSE) and molecular weight (Mn) (i.e.
crosslink density). The healing potential of SMP scaffolds will be evaluated in a critical size-rat calvarial model
using histological testing, micro-CT and biomechanical testing.
 The team is comprised of experts in all key areas of the proposed work. Prof. Melissa Grunlan (PI) will
lead efforts to prepare polydopamine-coated SMP scaffolds and uncoated controls (Aims 1-3). Prof. Mariah
Hahn (Co-I) will lead in vitro tissue engineering studies with rat- and human-BMSCs incorporated into the
scaffolds (Aim 2). Prof. Brian Saunders (Co-I) will implant cell-laden scaffolds into rat calvarial defects (Aim
3). Prof. Michael Moreno will lead efforts to study biomechanical properties of scaffolds, native tissues and
bone-graft constructs (Aims 1-3). Healing will be evaluated by histology/immunohistochemistry (Prof. Roy
Pool and Saunders, Co-Is), micro-CT (Saunders) and b...

## Key facts

- **NIH application ID:** 9852304
- **Project number:** 5R01DE025886-04
- **Recipient organization:** TEXAS ENGINEERING EXPERIMENT STATION
- **Principal Investigator:** Melissa Grunlan
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $488,792
- **Award type:** 5
- **Project period:** 2017-02-01 → 2021-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9852304

## Citation

> US National Institutes of Health, RePORTER application 9852304, Bioactive, "Self-fitting" Shape Memory Polymer (SMP) Scaffolds to Treat Cranial Bone Defects (5R01DE025886-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9852304. Licensed CC0.

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