3D-Printed Graphene-Based Scaffolds for Muscle-Derived Satellite Cell Differentiation in Denervation Injury

Project: Research project

Description

Denervation injuries are associated with devastating clinical effects, such as loss of hand function in proximal ulnar nerve injuries and facial droop and corneal exposure in facial nerve palsies. Following peripheral nerve injury, there is a metaphorical “race against the clock” to reestablish neural input to denervated skeletal muscle by 12-18 months for reasonable return of function. With a direct correlation to time, terminal Schwann cells at the neuromuscular junction (NMJ) retract their processes, resulting in loss of guiding endoneurial tracts and NMJ that are never reinnervated.2 Concomitant changes in denervated muscle result in atrophy, changes in sarcomere alignment, fibrillation potentials, and fatty replacement.3 While advances in peripheral nerve tissue engineering have incrementally increased the speed of peripheral nerve regeneration, the short window of viability of motor endplates remains a challenge to effective functional recovery and rehabilitation.
Our long-term objective is to recover function in denervated skeletal muscle. Previous strategies have included electrical stimulation of denervated muscle to delay atrophy and stimulate neurotrophic factors,4-6 “babysitter” nerve transfers and side-to-side nerve bridges to distal nerve stumps to provide a source of donor axons,6-8 and transplantation of various stem cell lines into the distal nerve stump and intramuscularly to promote neurogenesis.9,10 Taken together, these strategies are based on the scientific premise that successful muscle reinnervation relies on the maintenance of an intramuscular neurotrophic gradient while waiting for peripheral nerve regeneration to reach its target.11 While a favorable neurotrophic environment is essential, these strategies do not attempt to harness the regenerative mechanisms of muscle-derived stem cells (MDSC), which begin to proliferate upon muscle injury, but undergo a futile cycle of regeneration and atrophy in the absence of differentiation and maturation cues.3,12 MDSC have shown the capacity to differentiate into not only muscle, but also Schwann cell phenotypes.13 We propose a material-centric, tissue engineering approach using 3D-printed, electroconductive scaffolds, which will not only maintain a neurotrophic gradient, but will also stimulate host MDSC to differentiate into neuronal, glial, and muscle cells. Our central hypothesis is that host MDSC may be directed to neuronal, glial, and muscle differentiation and maturation by properties intrinsic to a biomaterial scaffold. We further hypothesize that co-regeneration of multiple dependent cell types will promote maturation of the respective cell types and neuromuscular junction (NMJ) formation.
We have developed high-content graphene-based material inks for 3-dimensional (3D)-printing that may be blended with other bioactive materials using a common polymer base and solvent system.1,14 We have demonstrated human mesenchymal stem cell (hMSC) differentiation into glial and neuron-like cells when cultured in vitro on 3D-printed graphene without exogenous biochemical or electrical cues.1 We have developed protocols for incorporating tissue-specific powders, derived from decellularized tissue matrices, into 3D-inks.15 Decellularized muscle matrices contain muscle-specific extracellular matrix (ECM) proteins and growth factors, which have consistently been shown to attract MDSC and stimulate myofiber formation. This effect is independent of matrix architecture, implying the importance of biochemistry over physical structure.16,17 Blending graphene inks with decellul
StatusActive
Effective start/end date7/1/196/30/21

Funding

  • American Association of Plastic Surgeons (Agmt 1/30/19)

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Graphite
Denervation
Cell Differentiation
Muscles
Wounds and Injuries
Stem Cells
Neuromuscular Junction
Peripheral Nerves
Neuroglia
Atrophy
Ink
Nerve Regeneration
Schwann Cells
Tissue Engineering
Regeneration
Skeletal Muscle
Substrate Cycling
Nerve Transfer
Facial Injuries
Motor Endplate