Tissue engineering is emerging as a possible alternative to methods aimed at alleviating the growing demand for replacement tissues and organs. A major pillar of most tissue engineering approaches is the scaffold, a biocompatible network of synthetic or natural polymers, which serves as an extracellular matrix mimic for cells. When the scaffold is seeded with cells it is supposed to provide the appropriate biomechanical and biochemical conditions for cell proliferation and eventual tissue formation. Numerous approaches have been used to fabricate scaffolds with ever-growing complexity. Recently, novel approaches have been pursued that do not rely on artificial scaffolds. The most promising ones utilize matrices of decellularized organs or methods based on multicellular self-assembly, such as sheet-based and bioprinting-based technologies. We briefly overview some of the scaffold-free approaches and detail one that employs biological self-assembly and bioprinting. We describe the technology and its specific applications to engineer vascular and nerve grafts.
Restoration of shoulder function is one of the most critical goals of treatment of brachial plexus injuries. Primary repair or nerve grafting of avulsion injuries of the upper brachial plexus in adults often leads to poor recovery. Nerve transfers have provided an alternative treatment with great potential for improved return of function. Many different nerves have been utilized as donor nerves for transfer to the suprascapular nerve and axillary nerve for return of shoulder function with variable results. As our knowledge of shoulder neuromuscular anatomy and physiology improves and our experience with nerve transfers increases, so evolve the specific transfer procedures. This article presents a technique and rationale for reconstructing shoulder function by transferring the distal spinal accessory nerve to the suprascapular nerve and the nerve branch to the medial head of the triceps to the axillary nerve, both through a posterior approach.
Modern nerve-to-nerve transfers represent one of the greatest advances in peripheral nerve surgery. Lessons of tendon transfers have taught that nerves to specific musculotendinous units are expendable, and greater understanding of peripheral nerve topography has revealed redundant fascicles in peripheral nerves. Transfer of these redundant or expendable nerves to recipient nerves close to the end organ allows for earlier reinnervation and preservation of those musculotendinous units. Such nerve transfers provide significantly better treatment options in many cases of nerve injury where previous outcomes were expected to be poor, such as with proximal injuries, long nerve gaps, or unavailability of the proximal injured segment. This article will review current nerve transfers in the hand and upper extremity.
This study reconfirms the authors' early findings that atraumatic harvest of lipoaspirate yields high cell counts and that adipocyte density is greatest at the lowest sublayer of centrifuged fat. The Viafill system provides a more efficient and user-friendly system for fat grafting while maintaining cell counts similar to the authors' technique using conventional equipment.
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