Examining the in vivo functionality of the Magnetically Aligned Regenerative Tissue-Engineered Electronic Nerve Interface (MARTEENI)

Development of Biomaterials for Addressing Upper Extremity Peripheral Nerve Gaps

Peripheral nerve injuries within the upper extremities can lead to impaired function and reduced quality of life. Although autografts have traditionally served as the primary therapeutic approach to bridge nerve gaps, these present challenges related to donor site morbidity. This review delves into the realm of biomaterials tailored for addressing nerve gaps. Biomaterials, whether natural or synthetically derived, offer the potential not only to act as scaffolds for nerve regeneration but also to be enhanced with growth factors and agents that promote nerve recovery. The historical progression of these biomaterials as well as their current applications, advantages, inherent challenges, and future impact in the arena of regenerative medicine are discussed. By providing a comprehensive overview, we aim to shed light on the transformative potential of biomaterials in peripheral nerve repair and the path toward refining their efficacy in clinical settings.

Clinical outcomes of peripheral nerve interfaces for rehabilitation in paralysis and amputation: a literature review

Peripheral nerve interfaces (PNIs) are electrical systems designed to integrate with peripheral nerves in patients, such as following central nervous system (CNS) injuries to augment or replace CNS control and restore function. We review the literature for clinical trials and studies containing clinical outcome measures to explore the utility of human applications of PNIs. We discuss the various types of electrodes currently used for PNI systems and their functionalities and limitations. We discuss important design characteristics of PNI systems, including biocompatibility, resolution and specificity, efficacy, and longevity, to highlight their importance in the current and future development of PNIs. The clinical outcomes of PNI systems are also discussed. Finally, we review relevant PNI clinical trials that were conducted, up to the present date, to restore the sensory and motor function of upper or lower limbs in amputees, spinal cord injury patients, or intact individuals and describe their significant findings. This review highlights the current progress in the field of PNIs and serves as a foundation for future development and application of PNI systems.

Regenerative Peripheral Nerve Interfaces (RPNIs) in Animal Models and Their Applications: A Systematic Review

Regenerative Peripheral Nerve Interfaces (RPNIs) encompass neurotized muscle grafts employed for the purpose of amplifying peripheral nerve electrical signaling. The aim of this investigation was to undertake an analysis of the extant literature concerning animal models utilized in the context of RPNIs. A systematic review of the literature of RPNI techniques in animal models was performed in line with the PRISMA statement using the MEDLINE/PubMed and Embase databases from January 1970 to September 2023. Within the compilation of one hundred and four articles employing the RPNI technique, a subset of thirty-five were conducted using animal models across six distinct institutions. The majority (91%) of these studies were performed on murine models, while the remaining (9%) were conducted employing macaque models. The most frequently employed anatomical components in the construction of the RPNIs were the common peroneal nerve and the extensor digitorum longus (EDL) muscle. Through various histological techniques, robust neoangiogenesis and axonal regeneration were evidenced. Functionally, the RPNIs demonstrated the capability to discern, record, and amplify action potentials, a competence that exhibited commendable long-term stability. Different RPNI animal models have been replicated across different studies. Histological, neurophysiological, and functional analyses are summarized to be used in future studies.

Reactive-Accelerated-Aging Testing of Thinned Tissue-Engineered Electronic Nerve Interfaces

Tissue responses can cause a significant reduction in the performance of microelectrode-based devices implanted into neural tissue. Since the reduction of the thickness of implants has been shown to reduce tissue response, in this work we report on our effects to reduce the thickness of our tissue-engineered-electronic-nerve-interface (TEENI) devices and characterize their long-term reliability in a harsh environment. We were able to reduce the thickness of the TEENI threads that are to be located in nerve tissue from ~10 μm to ~2.5 μm in total thickness. To maintain the handleability needed during the assembly of the TEENI device into the hydrogel-based scaffold, we maintained full thickness elsewhere in the TEENI device and added support rails. During longitudinal reactive-accelerated-aging (RAA) experiments performed over 6 days and at 67°C, which corresponds to ~48 days in tissue, we observed that some channels maintain a stable impedance and others do not. Although analyses performed using a scanning electron microscope could clearly reveal delamination in some channels that exhibited large changes in impedance, it did not always correlate. Some channels with significant changes in impedance did not exhibit any observable delamination. Additional work is needed to study the relationship between changes in impedance and structural changes in the device, with the goal of improving device design to achieve longer-lasting devices.