Seminar Series
Monday, April 22, 2024
Gateway Park, Room GP 1002
12am-12:50am
"Neuromuscular Derived Exosomes Enhance Neurite Development"
Hanson Lee, PhD Candidate
Skeletal muscles are the voluntary controlled muscle system that require intentional neural input. When critically injured, skeletal muscles develop scars and lose neural connection, functional contractility, and general mobility. Several approaches including implantable scaffolds, myogenic cells, and growth factors have yet to achieve complete functional regeneration. Another therapeutic avenue in development is extracellular vesicles called exosomes. Secreted from cells for signaling, exosomes contain various biomolecules that facilitate cellular response and development. Compared to most labs that characterize exosomes from individual cell sources, Dr. Pin's Lab in collaboration with Dr. Scarlata's Lab has exosomes derived from a coculture of skeletal muscle myoblasts and neuronal cells. This presentation will discuss the rationale for the novel exosome strategy, neurite outgrowth results when compared against different exosome sources and neural growth factor, and the therapeutic potential for exosomes derived from multi-cellular tissue systems.
“Leveraging the Structural Properties of Biologic Scaffolds to Promote Tissue Regeneration”
Bryanna Samolyk, PhD Candidate
Functional regeneration of anisotropically aligned tissues such as ligaments, microvascular networks, myocardium, or skeletal muscle requires a temporal and spatial series of biochemical and biophysical cues to direct cell functions that promote native tissue regeneration. When these cues are lost during traumatic injuries such as volumetric muscle loss (VML), scar formation occurs, limiting the regenerative capacity of the tissue. Currently, autologous tissue transfer is the gold standard for treating injuries such as VML, but can result in adverse outcomes including graft failure, donor site morbidity, and excessive scarring. Tissue engineered scaffolds composed of biomaterials, cells, or both, have been investigated to promote functional tissue regeneration. These scaffolds should provide precisely tuned topographies and stiffnesses using pro-regenerative materials to encourage tissue specific functions such as myoblast orientation in skeletal muscle, which is followed by aligned myotube formation and recovery of functional contraction. To address this, we describe the design and characterization of novel porous fibrin scaffolds with anisotropic microarchitectural features to recapitulate the native tissue microenvironment and offer a promising approach for regeneration of aligned tissues. We used directional freeze casting with varied fibrin concentrations and freezing temperatures to produce scaffolds with tunable degrees of anisotropy and strut widths. Nanoindentation analyses showed that the moduli of our fibrin scaffolds varied as a function of fibrin concentration and were consistent with native skeletal muscle tissue. Morphometric analyses of myoblast cytoskeletons on the scaffold structures demonstrated enhanced cell alignment as a function of microarchitectural morphology. The ability to precisely control the anisotropic features of fibrin scaffolds promises to provide a powerful tool for directing aligned tissue ingrowth and enhance functional regeneration of tissues such as skeletal muscle.
Additionally, functional regeneration of skin tissue in response to full-thickness injuries requires structural support for both dermal ingrowth and epidermal stratification, as well as a vascular network to support the metabolic demands of these proliferating tissues. Without treatment, these injuries result in extensive skin damage, scarring and permanent loss of function. The standard for closure of full-thickness burns are split-thickness skin autografts, however more extensive burns often require treatment with an allografts, xenografts, or skin substitutes because of insufficient donor sites. Skin substitutes, including acellular human matrices (i.e. AlloDerm), acellular animal matrices (i.e. Integra) and synthetic analogs (i.e. Biobrane), have demonstrated some success, but require 2-3 weeks for vascular integration and require a second surgical procedure to re-epithelialize the wound site. The absence of robust internal vascular networks assuring graft survival is the primary mode of failure for these skin substitutes. To address this, we aim to develop an implantable dermal scaffold that contains vascular networks to promote rapid vascularization and maximize functional tissue regeneration. Decellularized leaves can serve as provisional vascular beds to facilitate the rapid neovascularization of skin tissue. Previous data shows that leaf-derived vascular scaffolds (LeaVS) can be effectively decellularized, leaving the plant’s vascular structures intact while retaining desirable mechanical properties. Internal and external surfaces of these biocompatible scaffolds can be functionalized to facilitate attachment and proliferation of human cells. We show that scaffolds support growth of a contiguous layer of keratinocytes with characteristic cobblestone morphology and progressive epithelial stratification, as well as fibroblast attachment and proliferation. The ability to engineer LeaVS to direct cell functions promises to improve the rate of pro-regenerative endothelial, dermal, and epithelial tissue formation in a full thickness wound model.