Evaluation of Dexamethasone-Eluting Cell-Seeded Constructs in a Preclinical Canine Model of Cartilage Repair.

In this 12-month long, preclinical large animal study using a canine model, we report that engineered osteochondral grafts (comprised of allogeneic chondrocyte-seeded hydrogels with the capacity for sustained release of the corticosteroid dexamethasone [DEX], cultured to functional mechanical properties, and incorporated over porous titanium bases), can successfully repair damaged cartilage. DEX release from within engineered cartilage was hypothesized to improve initial cartilage repair by modulating the local inflammatory environment, which was also associated with suppressed degenerative changes exhibited by menisci and synovium. We note that not all histological and clinical outcomes at an intermediary time point of three months paralleled 12-month outcomes, which emphasizes the importance of studies in valid preclinical models that incorporate clinically relevant follow-up durations.

The Future of Microsurgery: Vascularized Composite Allotransplantation and Engineering Vascularized Tissue.

Background: Microsurgical techniques have revolutionized the field of reconstructive surgery and are the mainstay for complex soft tissue reconstruction. However, their limitations have promoted the development of viable alternatives. This article seeks to explore technologies that have the potential of revolutionizing microsurgical reconstruction as it is currently known, reflect on current and future vascularized composite allotransplantation (VCA) practices, as well as describe the basic science within emerging technologies and their potential translational applications.

Soft Tissue Reconstruction.

Autologous fat transplantation has revolutionized soft tissue reconstruction, but conventional methods remain unpredictable as graft resorption rates are high due to lack of vascularization. The advent of adipose-derived stem cells (ASCs) has led to improvement of fat grafting outcomes, in part to their ability to undergo facile differentiation into adipose tissue, their angiogenic properties, and their ability to express and secrete multiple growth factors. This chapter discusses the isolation and characterization of human ASCs, its expansion in vitro, and relevant in vivo models for adipose tissue engineering.

Biodegradable Nerve Guide with Glial Cell Line-Derived Neurotrophic Factor Improves Recovery After Facial Nerve Injury in Rats.

Bioengineered nerve guides with glial cell line-derived neurotrophic factor (GDNF) support recovery after facial nerve injury by acting as regenerative scaffolds. To compare functional, electrophysiological, and histological outcomes after repair of rat facial nerve transection in control, empty nerve guide, and nerve guide with GDNF conditions. Rats underwent transection and primary repair of the buccal branch of the facial nerve and were divided into (1) transection and repair only, (2) transection and repair augmented with empty guide, (3) transection and repair augmented with GDNF-guide groups.

Intramuscular Nanofat Injection Promotes Inflammation-Induced Gastrocnemius Regeneration in a Syngeneic Rat Sciatic Nerve Injury Model.

Background: Mechanical emulsification of adipose tissue to concentrate protein and stromal cell components (ie, nanofat) has gained considerable interest in clinical practice. Although the regenerative potential of nanofat has largely been used in aesthetic applications, these effects have considerable potential in reconstruction as well. Here, the authors investigated the therapeutic properties of nanofat injected directly into the denervated gastrocnemius after a sciatic nerve injury in Lewis rats.

Automated Decellularization of the Rodent Epigastric Free Flap: A Comparison of Sodium Dodecyl Sulfate-Based Protocols.

Background:  Free tissue transfer to cover complex wounds with exposed critical structures results in donor-site morbidity. Perfusion decellularization and recellularization of vascularized composite tissues is an active area of research to fabricate complex constructs without a donor site. Sodium dodecyl sulfate (SDS)-based protocols remain the predominant choice for decellularization despite the deleterious effects on tissue ultrastructure and capillary networks.

Intramuscular injection of skeletal muscle derived extracellular matrix mitigates denervation atrophy after sciatic nerve transection.

Peripheral nerve injury and the associated muscle atrophy has an estimated annual healthcare burden of $150 billion dollars in the United States. When considering the total annual health-related spending of $3.5 trillion, these pathologies alone occupy about 4.

Engineering a 3D Vascularized Adipose Tissue Construct Using a Decellularized Lung Matrix.

Critically sized defects in subcutaneous white adipose tissue result in extensive disfigurement and dysfunction and remain a reconstructive challenge for surgeons; as larger defect sizes are correlated with higher rates of complications and failure due to insufficient vascularization following implantation. Our study demonstrates, for the first time, a method to engineer perfusable, pre-vascularized, high-density adipose grafts that combine patient-derived adipose cells with a decellularized lung matrix (DLM). The lung is one of the most vascularized organs with high flow, low resistance, and a large blood-alveolar interface separated by a thin basement membrane.

Facial Nerve Repair: Bioengineering Approaches in Preclinical Models.

Injury to the facial nerve can occur after different etiologies and range from simple transection of the branches to varying degrees of segmental loss. Management depends on the extent of injury and options include primary repair for simple transections and using autografts, allografts, or conduits for larger gaps. Tissue engineering plays an important role to create artificial materials that are able to mimic the nerve itself without extra morbidity in the patients.

Evaluation of Porcine Versus Human Mesenchymal Stromal Cells From Three Distinct Donor Locations for Cytotherapy.

Mesenchymal stromal cell (MSC)-based cytotherapies fuel the hope for reduction of chronic systemic immunosuppression in allotransplantation, and our group has previously shown this capability for both swine and human cells. MSCs harvested from distinct anatomical locations may have different behavior and lead to different outcomes in both preclinical research and human trials. To provide an effective reference for cell therapy studies, we compared human and porcine MSCs from omental fat (O-ASC), subcutaneous fat (SC-ASC) and bone marrow (BM-MSC) under rapid culture expansion with endothelial growth medium (EGM).

Adipose-derived stem cells integrate into trabecular meshwork with glaucoma treatment potential.

The trabecular meshwork (TM) is an ocular tissue that maintains intraocular pressure (IOP) within a physiologic range. Glaucoma patients have reduced TM cellularity and, frequently, elevated IOP. To establish a stem cell-based approach to restoring TM function and normalizing IOP, human adipose-derived stem cells (ADSCs) were induced to differentiate to TM cells in vitro.

Long-gap peripheral nerve repair through sustained release of a neurotrophic factor in nonhuman primates.

Severe injuries to peripheral nerves are challenging to repair. Standard-of-care treatment for nerve gaps >2 to 3 centimeters is autografting; however, autografting can result in neuroma formation, loss of sensory function at the donor site, and increased operative time. To address the need for a synthetic nerve conduit to treat large nerve gaps, we investigated a biodegradable poly(caprolactone) (PCL) conduit with embedded double-walled polymeric microspheres encapsulating glial cell line-derived neurotrophic factor (GDNF) capable of providing a sustained release of GDNF for >50 days in a 5-centimeter nerve defect in a rhesus macaque model.

Sustained low-dose dexamethasone delivery via a PLGA microsphere-embedded agarose implant for enhanced osteochondral repair.

Articular cartilage defects are a common source of joint pain and dysfunction. We hypothesized that sustained low-dose dexamethasone (DEX) delivery via an acellular osteochondral implant would have a dual pro-anabolic and anti-catabolic effect, both supporting the functional integrity of adjacent graft and host tissue while also attenuating inflammation caused by iatrogenic injury. An acellular agarose hydrogel carrier with embedded DEX-loaded poly(lactic-co-glycolic) acid (PLGA) microspheres (DLMS) was developed to provide sustained release for at least 99 days.

Design and Fabrication of an Automatable, 3D Printed Perfusion Device for Tissue Infusion and Perfusion Engineering.

Tissue decellularization for generating extracellular matrices has become a staple of regenerative medicine in the recent decades, extending from the research setting to clinical usage. Although methods and protocols for tissue decellularization are abundant throughout the literature, they can be time intensive and typically require specific overhead in terms of equipment. To reduce these barriers to entry, a functional and reproducible prototype of a tissue infusion/perfusion device (TIPD) has been designed and fabricated using three-dimensional printed parts in conjunction with commercially available components.

Changing the Paradigm of Craniofacial Reconstruction: A Prospective Clinical Trial of Autologous Fat Transfer for Craniofacial Deformities.

Objective: This study aimed to prospectively assess outcomes for surgical autologous fat transfer (AFT) applied for traumatic and postsurgical craniofacial deformities. The minimally invasive nature of AFT has potential for reduced risk and superior outcomes compared with current reconstructive options.

Background: Craniofacial deformities have functional and psychosocial sequelae and can profoundly affect quality of life.

The Future of Facial Fat Grafting.

Fat grafting was first described in the early 20th century but for many years remained a relatively underused technique due to the unreliability of long-term volume expansion. Significant improvements in reliability have been made in the last 2 decades and there is a large body of literature pertaining to extraction, processing and injection methods to obtain more lasting effects. However, volume loss and graft resorption remain a major challenge in the long term and lead to unpredictability in results.

Adipose Stem Cells Enhance Nerve Regeneration and Muscle Function in a Peroneal Nerve Ablation Model.

Severe peripheral nerve injuries have devastating consequences on the quality of life in affected patients, and they represent a significant unmet medical need. Destruction of nerve fibers results in denervation of targeted muscles, which, subsequently, undergo progressive atrophy and loss of function. Timely restoration of neural innervation to muscle fibers is crucial to the preservation of muscle homeostasis and function.

Injectable Allograft Adipose Matrix Supports Adipogenic Tissue Remodeling in the Nude Mouse and Human.

Background: Adipose tissue reaches cellular stasis after puberty, leaving adipocytes unable to significantly expand or renew under normal physiologic conditions. This is problematic in progressive lipodystrophies, in instances of scarring, and in soft-tissue damage resulting from lumpectomy and traumatic deformities, because adipose tissue will not self-renew once damaged. This yields significant clinical necessity for an off-the-shelf de novo soft-tissue replacement mechanism.

Adipose-derived stem cells delay muscle atrophy after peripheral nerve injury in the rodent model.

Introduction: Injuries to peripheral nerves cause distal muscle atrophy. The effects of adipose-derived stem cell (ASC) injections into a muscle after injury were examined.

Methods: A 1.

Oncologic Safety of Fat Grafting for Autologous Breast Reconstruction in an Animal Model of Residual Breast Cancer.

Background: Clinical outcomes suggest that postoncologic reconstruction with fat grafting yields cumulative incidence curves of recurrence comparable to those of other breast reconstruction procedures; however, results from experimental research studies suggest that adipose stem cells can stimulate cancer growth. In this study, a novel animal model of residual cancer was developed in mouse mammary pads to test whether lipofilling impacts the probability of locoregional recurrence of breast cancer after breast conserving surgery.

Methods: Mammary fat pads of female NOD-SCID gamma mice were each injected with MCF-7 cells in Matrigel.

Characteristics and Immunomodulating Functions of Adipose-Derived and Bone Marrow-Derived Mesenchymal Stem Cells Across Defined Human Leukocyte Antigen Barriers.

Background: Vascularized composite allotransplantation opens new possibilities in reconstructive transplantation such as hand or face transplants. Lifelong immunosuppression and its side-effects are the main drawbacks of this procedure. Mesenchymal stem cells (MSCs) have clinically useful immunomodulatory effects and may be able to reduce the burden of chronic immunosuppression.

An exploratory study on the preparation and evaluation of a "same-day" adipose stem cell-based tissue-engineered vascular graft.

Objective: Tissue-engineered vascular grafts containing adipose-derived mesenchymal stem cells offer an alternative to small-diameter vascular grafts currently used in cardiac and lower-extremity revascularization procedures. Adipose-derived, mesenchymal stem cell-infused, tissue-engineered vascular grafts have been shown to promote remodeling and vascular homeostasis in vivo and offer a possible treatment solution for those with cardiovascular disease. Unfortunately, the time needed to cultivate adipose-derived mesenchymal stem cells remains a large hurdle for tissue-engineered vascular grafts as a treatment option.

Inflammatory biomarker in adipose stem cells of women with endometrial cancer.

Aim: To explore inflammatory biomarkers secreted by adipose stem cells (ASCs) in omental, retroperitoneal and subcutaneous adipose tissues of women with endometrial cancer.

Patients & Methods: ASCs were collected from 22 women, aged 35-83 years, undergoing hysterectomy for endometrial cancer. Angiopoietin-2, EGF, IL-8, leptin, VEGFA, VEGFC and VEFGD levels in the ASC-conditioned media were analyzed by Luminex.