Combination of tucatinib and neural stem cells secreting anti-HER2 antibody prolongs survival of mice with metastatic brain cancer.

Brain metastases are a leading cause of death in patients with breast cancer. The lack of clinical trials and the presence of the blood-brain barrier limit therapeutic options. Furthermore, overexpression of the human epidermal growth factor receptor 2 (HER2) increases the incidence of breast cancer brain metastases (BCBM). HER2-targeting agents, such as the monoclonal antibodies trastuzumab and pertuzumab, improved outcomes in patients with breast cancer and extracranial metastases. However, continued BCBM progression in breast cancer patients highlighted the need for novel and effective targeted therapies against intracranial metastases. In this study, we engineered the highly migratory and brain tumor tropic human neural stem cells (NSCs) LM008 to continuously secrete high amounts of functional, stable, full-length antibodies against HER2 (anti-HER2Ab) without compromising the stemness of LM008 cells. The secreted anti-HER2Ab impaired tumor cell proliferation in vitro in HER2+ BCBM cells by inhibiting the PI3K-Akt signaling pathway and resulted in a significant benefit when injected in intracranial xenograft models. In addition, dual HER2 blockade using anti-HER2Ab LM008 NSCs and the tyrosine kinase inhibitor tucatinib significantly improved the survival of mice in a clinically relevant model of multiple HER2+ BCBM. These findings provide compelling evidence for the use of HER2Ab-secreting LM008 NSCs in combination with tucatinib as a promising therapeutic regimen for patients with HER2+ BCBM.

Chronic Nicotine Exposure Alters the Neurophysiology of Habenulo-Interpeduncular Circuitry.

Antagonism of nicotinic acetylcholine receptors (nAChRs) in the medial habenula (MHb) or interpeduncular nucleus (IPN) triggers withdrawal-like behaviors in mice chronically exposed to nicotine, implying that nicotine dependence involves the sensitization of nicotinic signaling. Identification of receptor and/or neurophysiological mechanisms underlying this sensitization is important, as it could promote novel therapeutic strategies to reduce tobacco use. Using an approach involving photoactivatable nicotine, we previously demonstrated that chronic nicotine (cNIC) potently enhances nAChR function in dendrites of MHb neurons. However, whether cNIC modulates downstream components of the habenulo-interpeduncular (Hb-IP) circuit is unknown. In this study, cNIC-mediated changes to Hb-IP nAChR function were examined in mouse (male and female) brain slices using molecular, electrophysiological, and optical techniques. cNIC enhanced action potential firing and modified spike waveform characteristics in MHb neurons. Nicotine uncaging revealed nAChR functional enhancement by cNIC on proximal axonal membranes. Similarly, nAChR-driven glutamate release from MHb axons was enhanced by cNIC. In IPN, the target structure of MHb axons, neuronal morphology, and nAChR expression is complex, with stronger nAChR function in the rostral subnucleus [rostral IPN (IPR)]. As in MHb, cNIC induced strong upregulation of nAChR function in IPN neurons. This, coupled with cNIC-enhanced nicotine-stimulated glutamate release, was associated with stronger depolarization responses to brief (1 ms) nicotine uncaging adjacent to IPR neurons. Together, these results indicate that chronic exposure to nicotine dramatically alters nicotinic cholinergic signaling and cell excitability in Hb-IP circuits, a key pathway involved in nicotine dependence.SIGNIFICANCE STATEMENT This study uncovers several neuropharmacological alterations following chronic exposure to nicotine in a key brain circuit involved in nicotine dependence. These results suggest that smokers or regular users of electronic nicotine delivery systems (i.e., "e-cigarettes") likely undergo sensitization of cholinergic circuitry in the Hb-IP system. Reducing the activity of Hb-IP nAChRs, either volitionally during smoking cessation or inadvertently via receptor desensitization during nicotine intake, may be a key trigger of withdrawal in nicotine dependence. Escalation of nicotine intake in smokers, or tolerance, may involve stimulation of these sensitized cholinergic pathways. Smoking cessation therapeutics are only marginally effective, and by identifying cellular/receptor mechanisms of nicotine dependence, our results take a step toward improved therapeutic approaches for this disorder.

The influence of cyclic tensile strain on multi-compartment collagen-GAG scaffolds for tendon-bone junction repair.

Background: Orthopedic injuries often occur at the interface between soft tissues and bone. The tendon-bone junction (TBJ) is a classic example of such an interface. Current clinical strategies for TBJ injuries prioritize mechanical reattachment over regeneration of the native interface, resulting in poor outcomes. The need to promote regenerative healing of spatially-graded tissues inspires our effort to develop new tissue engineering technologies that replicate features of the spatially-graded extracellular matrix and strain profiles across the native TBJ. Materials and Methods: We recently described a biphasic collagen-glycosaminoglycan (CG) scaffold containing distinct compartment with divergent mineral content and structural alignment (isotropic vs. anisotropic) linked by a continuous interface zone to mimic structural and compositional features of the native TBJ. Results: Here, we report application of cyclic tensile strain (CTS) to the scaffold via a bioreactor leads to non-uniform strain profiles across the spatially-graded scaffold. Further, combinations of CTS and matrix structural features promote rapid, spatially-distinct differentiation profiles of human bone marrow-derived mesenchymal stem cells (MSCs) down multiple osteotendinous lineages. CTS preferentially upregulates MSC activity and tenogenic differentiation in the anisotropic region of the scaffold. This work demonstrates a tissue engineering approach that couples instructive biomaterials with cyclic tensile stimuli to promote regenerative healing of orthopedic interfaces.

Global Plastic Surgery: A Review of the Field and a Call for Virtual Training in Low- and Middle-Income Countries.

Lack of surgical access severely harms countless populations in many low- and middle-income countries (LMICs). Many types of surgery could be fulfilled by the plastic surgeon, as populations in these areas often experience trauma, burns, cleft lip and palate, and other relevant medical issues. Plastic surgeons continue to contribute significant time and energy to global health, primarily by participating in short mission trips intended to provide many surgeries in a short time frame. These trips, while cost-effective for lack of long-term commitments, are not sustainable as they require high initial costs, often neglect to educate local physicians, and can interfere with regional systems. Education of local plastic surgeons is a key step toward creating sustainable plastic surgery interventions worldwide. Virtual platforms have grown popular and effective-particularly due to the coronavirus disease 2019 pandemic-and have shown to be beneficial in the field of plastic surgery for both diagnosis and teaching. However, there remains a large potential to create more extensive and effective virtual platforms in high-income nations geared to educate plastic surgeons in LMICs to lower costs and more sustainably provide capacity to physicians in low access areas of the world.

Le manque d'accès à la chirurgie nuit sévèrement aux vastes populations de nombreux pays à revenus intermédiaires et faibles (PRIF). De nombreux types d'interventions chirurgicales pourraient être exécutés par les chirurgiens plastiques, car les populations de ces régions ont souvent des traumatismes, des brûlures, des fentes labio-palatines et d'autres problèmes médicaux pertinents. La chirurgie plastique continue d'accorder beaucoup de temps et d'énergie à la santé globale, principalement en participant à de courtes missions ayant pour but de résoudre de nombreux problèmes chirurgicaux dans un court laps de temps. Ces voyages, bien que rentables et influenceurs à court terme, n'ont pas d'effet durable, car ils ont des coûts initiaux élevés, négligent souvent d'éduquer les médecins locaux et peuvent perturber les systèmes régionaux. La formation de chirurgiens plastiques locaux est une étape essentielle pour la création d'interventions de chirurgie plastique durables dans le monde. Les plateformes virtuelles sont devenues populaires et efficaces, en particulier à cause de la pandémie de COVID-19, et ont montré leurs avantages dans le champ de la chirurgie plastique en matière de diagnostic et d'enseignement des divers facteurs de chirurgie plastique. Il existe un vaste potentiel pour la création de plateformes virtuelles permettant à des experts des pays à revenus élevés de former des chirurgiens plastiques de PRIF afin d'offrir des moyens plus rentables et durables à ces médecins exerçant dans des régions du monde où l'accès aux soins est plus limité.

Vascularized Bone Graft Reconstruction for Upper Extremity Defects: A Review.

Upper extremity reconstruction may pose clinical challenges for surgeons due to the often-critical, complex functional demands of the damaged and/or missing structures. The advent of vascularized bone grafts (VBGs) has aided in reconstruction of upper extremity (UE) defects due to their superior regenerative properties compared with nonvascularized bone grafts, ability to reconstruct large bony defects, and multiple donor site options. VBGs may be pedicled or free transfers and have the potential for composite tissue transfers when bone and soft tissue are needed. This article provides a comprehensive up-to-date review of VBGs, the commonly reported donor sites, and their indications for the treatment of specific UE defects.

Injectable allograft adipose matrices in the management of chronic and postoperative wounds: a retrospective analysis.

INTRODUCTION: Clinical options are lacking for the management of chronic wounds or ulcers following failed debridement, skin grafting, or negative pressure wound therapy dressings. OBJECTIVE: This retrospective case series evaluated the efficacy of injectable AAM in the management and closure of chronic wounds. MATERIALS AND METHODS: Patients with nonhealing wounds of any etiology, anatomic location, and length of chronicity were included; those with multiple chronic wounds or prior skin grafting for wound repair were excluded. Data on location, etiology, chronicity, and number of AAM applications were collected for each wound. Patients were evaluated for possible complications related to wound healing and infection. Eleven patients (7 males, 4 females), each with 1 chronic wound, were recruited (average age, 65 years). Wound etiologies were postoperative (n = 7), traumatic (n = 2), and foot ulcer (n = 2). Average wound dimensions were 8.45 mm × 7.36 mm, and the average chronicity was 3.77 months. Ten patients received only 1 application of AAM, and 1 patient received 2 treatments 5 days apart. Average follow-up time was 6.6 weeks. RESULTS: Seven patients (63%) achieved wound closure, 4 of which (57%) healed within 1 week of application. CONCLUSION: Most patients with chronic wounds treated with AAM experienced complete wound closure. AAM shows promising results for enhancing wound healing by providing scaffolding for cell growth.

Free Vascularized Fibular Flap with Bilateral Bipolar Latissimus Transfer for Upper Extremity Reconstruction: A Case Report.

CASE: A 19-year-old woman presented with bilateral mangled upper extremities after jumping in front of a moving train. After revascularization, osteocutaneous free vascularized fibula flap was performed to reconstruct the right humerus. The left forearm required transradial amputation with acute targeted muscle reinnervation. Finally, staged bilateral bipolar latissimus dorsi functional muscle flaps were performed to restore elbow flexion. CONCLUSION: Staged orthoplastic reconstruction of the upper extremities is an effective treatment approach for traumatic bone and soft-tissue defects. This patient's recovery demonstrates improved quality of life after severe upper extremity trauma.

Incorporating ß-cyclodextrin into collagen scaffolds to sequester growth factors and modulate mesenchymal stem cell activity.

The development of biomaterials for a range of tissue engineering applications increasingly requires control over the bioavailability of biomolecular cues such as growth factors in order to promote desired cell responses. While efforts have predominantly concentrated on covalently-bound or freely-diffusible incorporation of biomolecules in porous, three-dimensional biomaterials, opportunities exist to exploit transient interactions to concentrate growth factor activity over desired time frames. Here, we report the incorporation of ß-cyclodextrin into a model collagen-GAG scaffold as a means to exploit the passive sequestration and release of growth factors via guest-host interactions to control mesenchymal stem cell differentiation. Collagen-GAG scaffolds that incorporate ß-cyclodextrin show improved sequestration as well as extended retention and release of TGF-ß1. We further show extended retention and release of TGF-ß1 and BMP-2 from ß-cyclodextrin modified scaffolds was sufficient to influence the metabolic activity and proliferation of mesenchymal stem cells as well as differential activation of Smad 2/3 and Smad 1/5/8 pathways associated with differential osteo-chondral differentiation. Further, gene expression analysis showed TGF-ß1 release from ß-cyclodextrin CG scaffolds promoted early chondrogenic-specific differentiation. Ultimately, this work establishes a novel method for the incorporation and display of growth factors within CG scaffolds via supramolecular interactions. Such a design framework offers opportunities to selectively alter the bioavailability of multiple biomolecules within a three-dimensional collagen-GAG scaffold to enhance cell activity for a range of musculoskeletal regenerative medicine applications. STATEMENT OF SIGNIFICANCE: We describe the incorporation of ß-cyclodextrin into a model CG-scaffold under development for musculoskeletal tissue engineering applications. We show ß-cyclodextrin modified scaffolds promote the sequestration of soluble TGF-ß1 and BMP-2 via guest-host interactions, leading to extended retention and release. Further, ß-cyclodextrin modified CG scaffolds promote TGF-ß1 or BMP-2 specific Smad signaling pathway activation associated with divergent osseous versus chondrogenic differentiation pathways in mesenchymal stem cells.

Nicotinic Cholinergic Receptors in VTA Glutamate Neurons Modulate Excitatory Transmission.

Ventral tegmental area (VTA) glutamate neurons are important components of reward circuitry, but whether they are subject to cholinergic modulation is unknown. To study this, we used molecular, physiological, and photostimulation techniques to examine nicotinic acetylcholine receptors (nAChRs) in VTA glutamate neurons. Cells in the medial VTA, where glutamate neurons are enriched, are responsive to acetylcholine (ACh) released from cholinergic axons. VTA VGLUT2+ neurons express mRNA and protein subunits known to comprise heteromeric nAChRs. Electrophysiology, coupled with two-photon microscopy and laser flash photolysis of photoactivatable nicotine, was used to demonstrate nAChR functional activity in the somatodendritic subcellular compartment of VTA VGLUT2+ neurons. Finally, optogenetic isolation of intrinsic VTA glutamatergic microcircuits along with gene-editing techniques demonstrated that nicotine potently modulates excitatory transmission within the VTA via heteromeric nAChRs. These results indicate that VTA glutamate neurons are modulated by cholinergic mechanisms and participate in the cascade of physiological responses to nicotine exposure.