L1 Cell Adhesion Molecule (L1CAM) Expression and Molecular Alterations Distinguish Low-Grade Oncocytic Tumor From Eosinophilic Chromophobe Renal Cell Carcinoma.

Renal low-grade oncocytic tumor (LOT) is a recently recognized renal cell neoplasm designated within the "other oncocytic tumors" category in the 2022 World Health Organization classification system. Although the clinicopathologic, immunohistochemical, and molecular features reported for LOT have been largely consistent, the data are relatively limited. The morphologic overlap between LOT and other low-grade oncocytic neoplasms, particularly eosinophilic chromophobe renal cell carcinoma (E-chRCC), remains a controversial area in renal tumor classification. To address this uncertainty, we characterized and compared large cohorts of LOT (n = 67) and E-chRCC (n = 69) and revealed notable differences between the 2 entities. Clinically, LOT predominantly affected women, whereas E-chRCC showed a male predilection. Histologically, although almost all LOTs were dominated by a small-nested pattern, E-chRCC mainly showed solid and tubular architectures. Molecular analysis revealed that 87% of LOT cases harbored mutations in the tuberous sclerosis complex (TSC)-mTOR complex 1 (mTORC1) pathway, most frequently in MTOR and RHEB genes; a subset of LOT cases had chromosomal 7 and 19q gains. In contrast, E-chRCC lacked mTORC1 mutations, and 60% of cases displayed chromosomal losses characteristic of chRCC. We also explored the cell of origin for LOT and identified L1 cell adhesion molecule (L1CAM), a collecting duct and connecting tubule principal cell marker, as a highly sensitive and specific ancillary test for differentiating LOT from E-chRCC. This distinctive L1CAM immunohistochemical labeling suggests the principal cells as the cell of origin for LOT, unlike the intercalated cell origin of E-chRCC and oncocytoma. The ultrastructural analysis of LOT showed normal-appearing mitochondria and intracytoplasmic lumina with microvilli, different from what has been described for chRCC. Our study further supports LOT as a unique entity with a benign clinical course. Based on the likely cell of origin and its clinicopathologic characteristics, we propose that changing the nomenclature of LOT to "Oncocytic Principal Cell Adenoma of the Kidney" may be a better way to define and describe this entity.

Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy.

An instance of isolated unilateral temporalis muscle hypertrophy (reactive masticatory muscle hypertrophy with fiber type 1 predominance) confirmed by muscle biopsy with histochemical fiber typing and image analysis in a 62 year-old man is reported. The patient presented with bruxism and a painful swelling of the temple. Absence of asymmetry or other abnormalities of the craniofacial skeleton was confirmed by magnetic resonance imaging and cephalometric analyses. The patient achieved symptomatic improvement only after undergoing botulinum toxin injections. Muscle biopsy is key in the diagnosis of reactive masticatory muscle hypertrophy and its distinction from masticatory muscle myopathy (hypertrophic branchial myopathy) and other non-reactive causes of painful asymmetric temporalis muscle enlargement.

Mitochondrial dysfunction in neuromuscular disorders.

This review deciphers aspects of mitochondrial (mt) dysfunction among nosologically, pathologically, and genetically diverse diseases of the skeletal muscle, lower motor neuron, and peripheral nerve, which fall outside the traditional realm of mt cytopathies. Special emphasis is given to well-characterized mt abnormalities in collagen VI myopathies (Ullrich congenital muscular dystrophy and Bethlem myopathy), megaconial congenital muscular dystrophy, limb-girdle muscular dystrophy type 2 (calpainopathy), centronuclear myopathies, core myopathies, inflammatory myopathies, spinal muscular atrophy, Charcot-Marie-Tooth neuropathy type 2, and drug-induced peripheral neuropathies. Among inflammatory myopathies, mt abnormalities are more prominent in inclusion body myositis and a subset of polymyositis with mt pathology, both of which are refractory to corticosteroid treatment. Awareness is raised about instances of phenotypic mimicry between cases harboring primary mtDNA depletion, in the context of mtDNA depletion syndrome, and established neuromuscular disorders such as spinal muscular atrophy. A substantial body of experimental work, derived from animal models, attests to a major role of mitochondria (mt) in the early process of muscle degeneration. Common mechanisms of mt-related cell injury include dysregulation of the mt permeability transition pore opening and defective autophagy. The therapeutic use of mt permeability transition pore modifiers holds promise in various neuromuscular disorders, including muscular dystrophies.

Magnetically responsive paclitaxel-loaded biodegradable nanoparticles for treatment of vascular disease: preparation, characterization and in vitro evaluation of anti-proliferative potential.

Long term prevention of smooth muscle cell migration and proliferation inside the lumen of coronary arteries after stent implantation remains a challenge in medicine. Vascular stents have been coated with anti-proliferative drugs such as paclitaxel and rapamycin to improve the stents' efficacy. Maintaining adequate drug concentration on coronary stents presents an obstacle which magnetic nanoparticle (MNP) drug delivery could potentially overcome. Biodegradable, super-paramagnetic nanoparticles guided by high gradient magnetic fields have been proposed as transport vehicles for re-dosing stents with anti-proliferative drugs. The current study determined the characteristics of a number of candidate MNP formulations in terms of their size, surface charge, efficiency of magnetite and drug loadings, drug release profiles as well as their anti-proliferative effect on the relevant vascular cells. MNPs containing near 30% (w/w) magnetite and 12% (w/w) paclitaxel were formulated from polylactide and poly(lactide-co-glycolide) polymers using an emulsification-solvent evaporation methodology. Drug release patterns correlated well with cell growth inhibition in cultured aortic smooth muscle cells and bovine aortic endothelial cells treated with varying MNP doses. Cell viability assays revealed MNP dose-dependent cell growth inhibition over an 8-day time span for paclitaxel-loaded formulations resulting in near 80% and 100% of cell growth arrest in cultured vascular smooth muscle cells and endothelial cells respectively, while unloaded with drug formulations showed negligible variation from the non treated cells. It is concluded, that biodegradable polymeric superparamagnetic nanoparticles loaded with a relatively high level of magnetite and drug could serve as efficient carriers in vascular stent targeting applications and potentially allow re-dosing the depleted stents, thereby prolonging the lifecycle of the implant.

Efficient derivation of alveolar type II cells from embryonic stem cells for in vivo application.

In the present study, mouse embryonic stem cells (ESCs) were differentiated into alveolar epithelial type II (AEII) cells for endotracheal injection. These enriched lung-like populations expressed lung epithelial markers SP-A, SP-B, SP-C, and CC10. First we show that rapid differentiation of ESCs requires a dissociated seeding method instead of an embryoid body culture method. We then investigated a two-step differentiation of ESCs into definitive endoderm by activin or A549-conditioned medium as a precursor to lung epithelial cells. When conditioned medium from A549 cells was used to derive endoderm, yield was increased above that of activin alone. Further studies showed that Wnt3a may be one of the secreted factors produced by A549 cells and promotes definitive endoderm differentiation, in part, through suppression of primitive endoderm. Activin and Wnt3a together at appropriate doses with dissociated cell seeding promoted greater endoderm yield than activin alone. Next, fibroblast growth factor 2 was shown to induce a dose-dependent expression of SPC, and these cells contained lamellar bodies characteristic of mature AEII cells from ESC-derived endoderm. Finally, ES-derived lung cells were endotracheally injected into preterm mice with evidence of AEII distribution within the lung parenchyma. This study concludes that a recapitulation of development may enhance derivation of an enriched population of lung-like cells for use in cell-based therapy.

In vivo pulmonary tissue engineering: contribution of donor-derived endothelial cells to construct vascularization.

Intrapulmonary engraftment of engineered lung tissues could provide a potential therapeutic approach for the treatment of pediatric and adult pulmonary diseases. In working toward this goal, we report here on in vivo generation of vascularized pulmonary tissue constructs utilizing the subcutaneous Matrigel plug model. Mixed populations of murine fetal pulmonary cells (FPCs) containing epithelial, mesenchymal, and endothelial cells (ECs) were isolated from the lungs of embryonic day 17.5 fetuses. FPCs were admixed to Matrigel and injected subcutaneously into the anterior abdominal wall of adult C57/BL6 mice to facilitate in vivo pulmonary tissue construct formation. Vascularization was enhanced by placing fibroblast growth factor 2 (FGF2)-loaded polyvinyl sponges into the hydrogel. After 1 week, routine histology and immunohistochemical staining for donor-derived epithelial cells and ECs as well as analysis of patent vasculature in the constructs following tail vein injection of fluorescein isothiocyanate-conjugated dextran were performed. In the Matrigel-only controls, some level of host infiltrate, but no measurable vascularization, was detected. In the presence of FPCs, the constructs contained ductal epithelial structures and patent vasculature. In the absence of FPCs, exogenous FGF2 induced the formation of numerous patent blood vessels throughout the entire constructs; in combination with FPCs, it resulted in enhanced capillary density and abundant interfacing between developing epithelial and vascular structures. The significant findings of this study are that distal pulmonary epithelial differentiation (as assessed by the expression of prosurfactant protein C) can be maintained in vivo and that donor-derived ECs contribute to the formation of patent vessels that interface tightly with ductal epithelial structures.

Novel methods for delivery of cell-based therapies.

BACKGROUND: Pulmonary hypoplasia (PH) is found in 15% to 20% of all neonatal autopsies, accounting for 2850 deaths yearly. Development of engineered tissue substitutes that could functionally restore damaged tissue remains a unique opportunity for biotechnology. Recently, we isolated and characterized murine fetal pulmonary cells (FPC) and engineered 3-D pulmonary tissue constructs in vitro. Our goal is to devise a reliable and reproducible method for delivering FPC into a live animal model of PH. MATERIALS AND METHODS: Three methods of delivery were explored: intraoral, intratracheal, and intrapulmonary injection. Adult Swiss Webster mice were anesthetized and fluorescent labeled microspheres (20 microm diameter) were delivered by intraoral and intratracheal injection. Subsequently, labeled FPC (Cell Tracker, CMTPX; Molecular Probes, Eugene, OR) were delivered by the same methods. In addition, direct transpleural intrapulmonary injection of FPC was performed. Outcome analysis included survival, reproducibility, diffuse versus confined location of the injected substance, and adequacy of delivery. Routine histological examination, fluorescent microscopy, and immunostaining were performed. RESULTS: Microspheres: We demonstrated reproducible, diffuse instillation via tracheotomy into the distal alveoli. Intraoral delivery appeared less reliable compared to direct intratracheal injection. FPC: Intratracheal injection was a reliable method of delivery. Labeled FPC showed transepithelial migration after 7 d of in vivo culture. Intrapulmonary injection led to local accumulation of cells in sites of injection. CONCLUSIONS: We demonstrate that delivery of FPC is feasible with intratracheal injection giving the most reliable, diffuse delivery throughout the lung. This represents the first step toward translational research with site-specific delivery for a cell-based therapeutic approach toward PH and similar pulmonary diseases.

Engineering three-dimensional pulmonary tissue constructs.

In this paper, we report on engineering 3-D pulmonary tissue constructs in vitro. Primary isolates of murine embryonic day 18 fetal pulmonary cells (FPC) were comprised of a mixed population of epithelial, mesenchymal, and endothelial cells as assessed by immunohistochemistry and RT-PCR of 2-D cultures. The alveolar type II (AE2) cell phenotype in 2-D and 3-D cultures was confirmed by detection of SpC gene expression and presence of the gene product prosurfactant protein C. Three-dimensional constructs of FPC were generated utilizing Matrigel hydrogel and synthetic polymer scaffolds of poly-lactic-co-glycolic acid (PLGA) and poly-L-lactic-acid (PLLA) fabricated into porous foams and nanofibrous matrices, respectively. Three-dimensional Matrigel constructs contained alveolar forming units (AFU) comprised of cells displaying AE2 cellular ultrastructure while expressing the SpC gene and gene product. The addition of tissue-specific growth factors induced formation of branching, sacculated epithelial structures reminiscent of the distal lung architecture. Importantly, 3-D culture was necessary for inducing expression of the morphogenesis-associated distal epithelial gene fibroblast growth factor receptor 2 (FGFr2). PLGA foams and PLLA nanofiber scaffolds facilitated ingrowth of FPC, as evidenced by histology. However, these matrices did not support the survival of distal lung epithelial cells, despite the presence of tissue-specific growth factors. Our results may provide the first step on the long road toward engineering distal pulmonary tissue for augmenting and/or replacing dysfunctional native lung in diseases, such as neonatal pulmonary hypoplasia.