# Bionic Self-Stimulated Cartilage

> **NIH NIH R21** · UNIVERSITY OF CONNECTICUT STORRS · 2020 · $278,769

## Abstract

Millions of American go through total knee replacement every year due to osteoarthritis. Surgical
treatment of this disease is to implant replacement auto or allografts. Despite many advantages, these grafts
poses several limitations including limit of supplies, donor site morbidity (for autografts) and immune response
(in case of allografts). Consequently, engineered grafts - constructed in vitro by culturing autologous
chondrocytes on synthetic biomaterial scaffolds – have received attentions. Yet, they also exhibit issues, one of
which is the inefficiency of seeded-chondrocytes in these grafts to generate hyaline cartilages after implantation,
preventing their widespread use. As such, we believe it is necessary to seek for a new approach to effectively
stimulate and accelerate cartilage growth from commonly-used chondrocyte-seeded grafts, enhancing the grafts’
healing and regeneration capability.
 Electrical stimulation (ES) have been shown to exhibit profound effects on cartilage and bone
repair/regeneration. However, current ES devices present many drawbacks including inefficiency of generated
electrical field (for external ES devices), bulky size and toxic materials used in electrical stimulators, and non-
degradability of implanted ES devices.
 Piezoelectric materials, which can generate electrical signals from deformation and vice versa, can be
employed to create self-powered electrical stimulators. Interestingly, Poly-L-Lactid acid (PLLA), a biodegradable
polymer which has been used in many medical implants, can exhibit piezoelectricity when being processed
properly. Although not having a high piezoelectric constant, PLLA, owing to its low dielectric parameter, exhibits
the same efficiency for energy conversion as the common Polyvinylidene fluoride (PVDF) polymer.
 In this project, we study the science and technology to create a biodegradable, highly efficient
piezoelectric PLLA stimulator and integrate the stimulator with a biological chondrocyte-seeded cartilage graft,
forming a bionic cartilage tissue. Hypothetically, this bionic cartilage will create a feedback loop in which more
damaging joint-forces imparted on the cartilage would generate more useful electricity, which in turn enhances
cartilage growth. Once less force is exerted on the implant, the graft will be subject to less electrical stimulation,
avoiding harmful overdosing effect of electrical current on cartilage cells. The generated electrical outputs – in
response to joint force - can be tailored and optimized by altering PLLA film’s properties (e.g. thickness,
molecular weight, piezoelectric efficiency and number of PLLA layers etc.). As such, this “smart” bionic cartilage
will offer an innovative approach, optimizing electric stimulation for cartilage repair and regeneration from
autologous chondrocyte-seeded grafts.

## Key facts

- **NIH application ID:** 9913514
- **Project number:** 5R21EB024787-03
- **Recipient organization:** UNIVERSITY OF CONNECTICUT STORRS
- **Principal Investigator:** Thanh Nguyen
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $278,769
- **Award type:** 5
- **Project period:** 2017-07-15 → 2022-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9913514

## Citation

> US National Institutes of Health, RePORTER application 9913514, Bionic Self-Stimulated Cartilage (5R21EB024787-03). Retrieved via AI Analytics 2026-05-27 from https://api.ai-analytics.org/grant/nih/9913514. Licensed CC0.

---

*[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*