Retinal Explant Culture from Mouse, Human, and Nonhuman Primates and Its Applications in Vision Research.

The retinal explant culture system is a valuable tool for studying the pharmacological, toxicological, and developmental aspects of the retina. It is also used for translational studies such as gene therapy. While no photoreceptor-like cell lines are available for in vitro studies of photoreceptor cell biology, the retinal explant culture maintains the laminated retinal structure ex vivo for as long as a month. Human and nonhuman primate (NHP) postmortem retinal explants cut into small pieces offer the possibility of testing multiple conditions for safety and adeno-associated viral (AAV) vector optimization. In addition, the cone-enriched foveal area can be studied using the retinal explants. Here, we present a detailed working protocol for retinal explant isolation and culture from mouse, human, and NHP for testing drug efficacy and AAV transduction. Future applications of this protocol include combining live imaging and multiwell retinal explant culture for high-throughput drug screening systems in rodent and human retinal explants to identify new drugs against retinal degeneration.

Isolation and Characterization of Human Dental Pulp Stem Cells Derived from Dental Pulp of Permanent Teeth.

Dental pulp stem cells (DPSCs) are a promising alternative to the source of mesenchymal stem cells (MSCs), as they are readily available in minimally invasive procedures compared to more invasive methods associated with harvesting other MSCs sources. Despite the encouraging pre-clinical outcomes in animal disease models, culture-expanding procedures are needed to obtain a sufficient number of MSCs required for delivery to the damaged site. However, this contributes to increasing regulatory difficulties in translating stem cells and tissue engineering therapy to clinical use. Moreover, discussions continue as to which isolation method is to be preferred when obtaining DPSCs from extracted molars. This protocol describes a simple explant isolation technique of human dental pulp stem cells from the dental pulp of permanent teeth based upon the plastic adherence of MSCs and subsequent outgrowth of cells out of tissue fragments with high efficacy.

An Enzyme-Free Method for Isolation and Expansion of Muscle Stem Cells for Cultivated Meat Applications.

Cultivated meat, an alternative to conventional meat, holds great promise in alleviating environmental and ethical concerns. Skeletal muscle stem cell isolation is a critical phase in cultivated meat production, and efficiency is a major determinant in the final differentiated muscle cell yield. The conventional enzymatic dissociation method for cell isolation presents drawbacks, including added costs and the destruction of vital extracellular matrix components. We developed an alternative cell isolation technique, explant cell isolation, to isolate muscle stem cells from muscle tissue. The present protocol yields myogenic cell populations, mainly composed of skeletal muscle stem cells without the use of enzymes, and through a simplified process. Overall, the explant method allows for propagation of cells in their natural environment, preserving intricate cell-cell and cell-matrix interactions, resulting in both economic efficiency and consistent generation of high-quality cells.

Development of a 3-dimensional organotypic model with characteristics of peripheral sensory nerves.

We developed a rat dorsal root ganglion (DRG)-derived sensory nerve organotypic model by culturing DRG explants on an organoid culture device. With this method, a large number of organotypic cultures can be produced simultaneously with high reproducibility simply by seeding DRG explants derived from rat embryos. Unlike previous DRG explant models, this organotypic model consists of a ganglion and an axon bundle with myelinated A fibers, unmyelinated C fibers, and stereo-myelin-forming nodes of Ranvier. The model also exhibits Ca2+ signaling in cell bodies in response to application of chemical stimuli to nerve terminals. Further, axonal transection increases the activating transcription factor 3 mRNA level in ganglia. Axons and myelin are shown to regenerate 14 days following transection. Our sensory organotypic model enables analysis of neuronal excitability in response to pain stimuli and tracking of morphological changes in the axon bundle over weeks.

Comprehensive analysis of substernal lead removal: experience from EV ICD Pilot, Pivotal, and Continued Access Studies.

BACKGROUND AND AIMS: The extravascular implantable cardioverter-defibrillator (EV ICD) has been shown to be safe and effective for patients at risk of sudden cardiac death, but little is known about EV ICD lead removal in humans. This analysis aimed to characterize the EV ICD lead removal experience thus far. METHODS: This was a retrospective analysis of lead removals from the EV ICD Pilot, Pivotal, and Continued Access Studies. Patients with a successful EV ICD implant who underwent lead removal were included. The main objective was lead removal success. Ancillary objectives included characterizing technique used, procedure complications, and reimplantation status. RESULTS: An EV ICD system was successfully implanted in 347 patients across the 3 studies (25.9% female; 53.4±13.3 years; LVEF: 39.7±15.9). Of these patients, 29 (8.4%) underwent lead removal with a mean lead dwell time of 12.6±14.3 months (0.2-58.4). The main reason for lead removal was lead dislodgement (n=9, 31.0%). Lead removal was successful in 27/29 (93.1%) cases [100% (19/19) success rate <1 year and 80% (8/10) success rate >1-year post-implant]. Simple traction was used in 22/26 (84.6%) and extraction tools in 4/26 (15.4%) successful cases where technique was known. No complications were reported for any of the removal procedures. All 11 EV ICD reimplant attempts were successful. CONCLUSIONS: Complete removal of the EV ICD lead was successful in 93.1% of cases and simple traction was sufficient in most instances. Based on these results, lead removal from the substernal space was safe and achievable up to 3 years post-implant.

Like Father like Daughter: Surgical Redo Thoracoabdominal Aneurysm Repairs in a Family With Loeys-Dietz Syndrome.

Loeys Dietz Syndrome (LDS) is an autosomal dominant connective tissue disorder resulting from a mutation in the transforming growth factor beta receptor (TGFBR) family of genes. It is commonly associated with the development of aortic aneurysms and dissections. We report the successful open surgical management of thoracoabdominal aneurysms in a father and daughter with Loeys-Dietz Syndrome after failed endovascular repair. The daughter required stent graft explantation, while the stent graft remained in the father. These cases highlight the importance of early genetic testing of both patients and first-degree family members in those with a strong history of aortic disease, even when there is a lack of typical connective tissue disorder associated physical exam findings and open surgical index operations.

In vitro assessment of nanomedicines' propensity to cause palmar-plantar erythrodysesthesia: A Doxil vs. doxorubicin case study.

Palmar-plantar erythrodysesthesia (PPE), also known as hand and foot syndrome, is a condition characterized by inflammation-mediated damage to the skin on the palms and soles of the hands and feet. PPE limits the successful therapeutic applications of anticancer drugs. However, identifying this toxicity during preclinical studies is challenging due to the lack of accurate in vitro and in vivo animal-based models. Therefore, there is a need for reliable models that would allow the detection of this toxicity early during the drug development process. Herein, we describe the use of an in vitro skin explant assay to assess traditional DXR, Doxil reference listed drug (RLD) and two generic PEGylated liposomal DXR formulations for their abilities to cause inflammation and skin damage. We demonstrate that the results obtained with the in vitro skin explant assay model for traditional DXR and Doxil correlate with the clinical data.

Photobiomodulation Using 830 nm Lighting-Emitting Diode Inhibits Melanogenesis via FOXO3a in Human Melanocyte.

Photobiomodulation (PBM) using 830 nm light-emitting diode (LED) benefits tissue regeneration, wound healing and neural stimulation. However, there is not much exploration of its effect on melanocytes and ex vivo skin model. This study aims to investigate the mechanism behind the anti-melanogenic activity of 830 nm LED and provides evidence for its activity in human ex vivo skin model. Our results showed that 830 nm LED at fluences ranging from 5 to 20 J/cm2 inhibited melanosome maturation and reduced melanin content, tyrosinase activity and melanogenesis-related proteins. 830 nm LED inhibited the phosphorylation of AKT and its downstream FOXO3a, leading to nuclear translocation of FOXO3a. Furthermore, FOXO3a knockdown and AKT activator like SC79 could reverse the melanogenesis inhibition phenotype induced by 830 nm LED. In human ex vivo skin model, Fontana-Masson staining revealed a decrease in epidermal basal pigmentation after 830 nm LED irradiation. Taken together, 830 nm LED demonstrated the anti-melanogenic activity via FOXO3a.

Cellular senescence impairs tendon extracellular matrix remodeling in response to mechanical unloading.

Musculoskeletal injuries, including tendinopathies, present a significant clinical burden for aging populations. While the biological drivers of age-related declines in tendon function are poorly understood, it is well accepted that dysregulation of extracellular matrix (ECM) remodeling plays a role in chronic tendon degeneration. Senescent cells, which have been associated with multiple degenerative pathologies in musculoskeletal tissues, secrete a highly pro-inflammatory senescence-associated secretory phenotype (SASP) that has potential to promote ECM breakdown. However, the role of senescent cells in the dysregulation of tendon ECM homeostasis is largely unknown. To assess this directly, we developed an in vitro model of induced cellular senescence in murine tendon explants. This novel technique enables us to study the isolated interactions of senescent cells and their native ECM without interference from age-related systemic changes. We document multiple biomarkers of cellular senescence in induced tendon explants including cell cycle arrest, apoptosis resistance, and sustained inflammatory responses. We then utilize this in vitro senescence model to compare the ECM remodeling response of young, naturally aged, and induced-senescent tendons to an altered mechanical stimulus. We found that both senescence and aging independently led to alterations in ECM-related gene expression, reductions in protein synthesis, and tissue compositional changes. Furthermore, MMP activity was sustained, thus shifting the remodeling balance of aged and induced-senescent tissues towards degradation over production. Together, this demonstrates that cellular senescence plays a role in the altered mechano-response of aged tendons and likely contributes to poor clinical outcomes in aging populations.

Recovery kinetics of dual AAV-mediated human otoferlin expression.

Deafness-causing deficiencies in otoferlin (OTOF) have been addressed preclinically using dual adeno-associated virus (AAV)-based approaches. However, timing of transduction, recombination of mRNA, and protein expression with dual hybrid AAV methods methods have not previously been characterized. Here, we have established an ex vivo assay to determine the kinetics of dual-AAV mediated expression of OTOF in hair cells of the mouse utricle. We utilized two different recombinant vectors that comprise DB-OTO, one containing the 5' portion of OTOF under the control of the hair cell-specific Myo15 promoter, and the other the 3' portion of OTOF. We explored specificity of the Myo15 promoter in hair cells of the mouse utricle, established dose response characteristics of DB-OTO ex vivo in an OTOF-deficient mouse model, and demonstrated tolerability of AAV1 in utricular hair cells. Furthermore, we established deviations from a one-to-one ratio of 5' to 3' vectors with little impact on recombined OTOF. Finally, we established a plateau in quantity of recombined OTOF mRNA and protein expression by 14 to 21 days ex vivo with comparable recovery timing to that in vivo model. These findings demonstrate the utility of an ex vivo model system for exploring expression kinetics and establish in vivo and ex vivo recovery timing of dual AAV-mediated OTOF expression.

Tissue explants as tools for studying the epigenetic modulation of the GH-IGF-I axis in farmed fish.

Somatic growth in vertebrates is mainly controlled by the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. The role of epigenetic mechanisms in regulating this axis in fish is far from being understood. This work aimed to optimize and evaluate the use of short-term culture of pituitary and liver explants from a farmed fish, the gilthead seabream Sparus aurata, for studying epigenetic mechanisms involved in GH/IGF-I axis regulation. Our results on viability, structure, proliferation, and functionality of explants support their use in short-term assays. Pituitary explants showed no variation in gh expression after exposure to the DNA methylation inhibitor decitabine (5-Aza-2'-deoxycytidine; DAC), despite responding to DAC by changing dnmt3bb and tet1 expression, and TET activity, producing an increase in overall DNA hydroxymethylation. Conversely, in liver explants, DAC had no effects on dnmt s and tet s expression or activity, but modified the expression of genes from the GH-IGF-I axis. In particular, the expression of igfbp2a was increased and that of igfbp4, ghri and ghrii was decreased by DAC as well as by genistein, which is suggestive of impaired growth. While incubation of liver explants with S-adenosylmethionine (SAM) produced no clear effects, it is proposed that nutrients must ensure the methylation milieu within the liver in the fish to sustain proper growth, which need further in vivo verification. Pituitary and liver explants from S. aurata can be further used as described herein for the screening of inhibitors or activators of epigenetic regulators, as well as for assessing epigenetic mechanisms behind GH-IGF-I variation in farmed fish.

3D Culture Analysis of Cancer Cell Adherence to Ex Vivo Lung Microexplants.

Ex vivo 3D culture of human tissue explants addresses many limitations of traditional monolayer cell culture techniques, namely the lack of cellular heterogeneity and absence of 3D intercellular spatial relationships, but presents challenges with regard to repeatability owing to the difficulty of acquiring multiple tissue samples from the same donor. In this study, we used a cryopreserved bank of human lung microexplants, ∼1 mm3 fragments of peripheral lung from donors undergoing lung resection surgery, and a liquid-like solid 3D culture matrix to describe a method for the analysis of non-small-cell lung cancer adhesion to human lung tissue. H226 (squamous cell carcinoma), H441 (lung adenocarcinoma), and H460 (large cell carcinoma) cell lines were cocultured with lung microexplants. Confocal fluorescence microscopy was used to visualize the adherence of each cell line to lung microexplants. Adherent cancer cells were quantified following filtration of nonadherent cells, digestion of cultured microexplants, and flow cytometry. This method was used to evaluate the role of integrins in cancer cell adherence. A statistically significant decrease in the adherence of H460 cells to lung microexplants was observed when anti-integrins were administered to H460 cells before coculture with lung microexplants.

An Efficient and Rapid Protocol for Somatic Shoot Organogenesis from Juvenile Hypocotyl-Derived Callus of Castor Bean cv. Zanzibar Green.

Aseptic seedlings of different ages derived from surface-sterilized mature seeds were applied as an explant source. Various explants such as 7- and 21-day-old hypocotyl fragments, 42-day-old nodal stem segments, and transverse nodal segments of stem, as well as leaf petioles, were cultured on the agar-solidified Murashige and Skoog (MS) basal medium supplemented with 0.1 mg/L IAA, 5 mg/L AgNO3 and different types and concentrations of cytokinin (1 mg/L zeatin, 0.25 mg/L thidiazuron (TDZ), and 5 mg/L 6-benzylaminopurine (6-BAP)). Consequently, it was found that 7- and 21-day-old hypocotyl fragments, as well as nodal stem segments obtained from adult aseptic seedlings, are characterized by a high explant viability and callus formation capacity with a frequency of 79.7-100%. However, the success of in vitro somatic shoot organogenesis was significantly determined not only by the culture medium composition and explant type but also depending on its age, as well as on the size and explant preparation in cases of hypocotyl and age-matched nodal stem fragments, respectively. Multiple somatic shoot organogenesis (5.7 regenerants per explant) with a frequency of 67.5% was achieved during 3 subcultures of juvenile hypocotyl-derived callus tissue on MS culture medium containing 0.25 mg/L TDZ as cytokinin source. Castor bean regenerants were excised from the callus and successfully rooted on ½ MS basal medium without exogenous auxin (81%). In vitro plantlets with well-developed roots were adapted to ex vitro conditions with a frequency of 90%.

Establishing Three-Dimensional Explant Culture of Human Dental Pulp Tissue.

Mesenchymal stem cells in the dental tissue indicate a disposition for differentiation into diverse dental lineages and contain enormous potential as the important means for regenerative medicine in dentistry. Among various dental tissues, the dental pulp contains stem cells, progenitor cells and odontoblasts for maintaining dentin homeostasis. The conventional culture of stem cells holds a limit as the living tissue constitutes the three-dimensional (3D) structure. Recent development in the organoid cultures have successfully recapitulated 3D structure and advanced to the assembling of different types. In the current study, the protocol for 3D explant culture of the human dental pulp tissue has been established by adopting the organoid culture. After isolating dental pulp from human tooth, the intact tissue was placed between two layers for Matrigel with addition of the culture medium. The reticular outgrowth of pre-odontoblast layer continued for a month and the random accumulation of dentin was observed near the end. Electron microscopy showed the cellular organization and in situ development of dentin, and immunohistochemistry exhibited the expression of odontoblast and stem cell markers in the outgrowth area. Three-dimensional explant culture of human dental pulp will provide a novel platform for understanding stem cell biology inside the tooth and developing the regenerative medicine.

Total Capsulectomy Without Drains is a Safe Technique Facilitated by Pectoralis Major Muscle Repair.

BACKGROUND: The number of breast implant removal and capsulectomy procedures continues to increase rapidly. The aim of explant surgery should be to optimise patient outcomes from both an aesthetic and functional perspective. OBJECTIVES: To confirm the safety of drainless total capsulectomy and to determine the role of muscle repair in explant outcomes following the removal of sub-pectoral or dual-plane cosmetic breast implants. METHODS: We conducted a retrospective evaluation of our technique between January 2021 and November 2023. We report a single surgeon series of 140 consecutive cases of cosmetic breast implant removal from dual-plane or sub-pectoral pockets, all performed with total capsulectomy. In each case, meticulous repair of the Pectoralis major muscle was performed following capsulectomy. Drains were not used in any case. All patients were followed up for a minimum of 3 months. Patient satisfaction was assessed a minimum of 6 months post-operatively. RESULTS: By performing the described drainless technique, there were no cases of seroma, haematoma, pneumothorax or cosmetic breast distortion in this series. 83% of patients were treated as day cases and patient satisfaction with outcomes was high. CONCLUSIONS: Total capsulectomy without the use of drains is a novel and safe approach, aided by careful repair of the Pectoralis major muscle. There is no increased risk of seroma. The muscle repair may help to prevent post-explant cosmetic deformity of the breast. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

An In Vitro Human Skin Test for Predicting Skin Sensitization and Adverse Immune Reactions to Biologics.

Biologics, including monoclonal antibodies (mAb), have proved to be effective and successful therapeutic agents, particularly in the treatment of cancer and immune-inflammatory conditions, as well as allergies and infections. However, their use carries an inherent risk of an immune-mediated adverse drug reaction. In this study, we describe the use of a novel pre-clinical human in vitro skin explant test for predicting skin sensitization and adverse immune reactions. The skin explant test was used to investigate the effects of therapeutic antibodies, which are known to cause a limited reaction in a small number of patients or more severe reactions. MATERIAL AND METHODS: Immune responses were determined by T cell proliferation and multiplex cytokine analysis, as well as histopathological analysis of skin damage (grades I-IV in increasing severity), predicting a negative (grade I) or positive (grade ≥ II) response for an adverse skin sensitization effect. RESULTS: T cell proliferation responses were significantly increased in the positive group (p < 0.004). Multiplex cytokine analysis showed significantly increased levels of IFNγ, TNFα, IL-10, IL-12, IL-13, IL-1ß, and IL-4 in the positive response group compared with the negative response group (p < 0.0001, p < 0.0001, p < 0.002, p < 0.01, p < 0.04, p < 0.006, and p < 0.004, respectively). CONCLUSIONS: Overall, the skin explant test correctly predicted the clinical outcome of 13 out of 16 therapeutic monoclonal antibodies with a correlation coefficient of 0.770 (p = 0.0001). This assay therefore provides a valuable pre-clinical test for predicting adverse immune reactions, including T cell proliferation and cytokine release, both associated with skin sensitization to monoclonal antibodies.

Transfection, cytotoxicity, and cell cycle studies on the two newly developed and characterized humpback grouper (Cromileptes altivelis) fin cell lines.

The development and characterization of two novel humpback grouper (Cromileptes altivelis) fin cell lines are described in this study. The CA1F3Ex and CA1F4Tr cell lines were developed by explant and trypsinization methods, respectively, in Leibovitz's L15 (L-15) medium supplemented with 20% FBS (fetal bovine serum) and subcultured over 150 times. Cell lines exhibited high stability, as evidenced by the high revival rate (85-95%) and good attachment while seeding after one year of cryostorage. They displayed good seeding (91%) and plating efficiencies (15-25%). The optimum temperature for growth was recorded at 28˚C. Serum requirement decreased with increased passage and lowered to 2% FBS beyond 30-35 passages. However, higher serum concentration (2-20%) caused a concurrent increase in cell growth. Both the cell lines were fibroblast-type, and immunotyping results showed strong reactivity towards the fibroblast marker. Chromosome analysis of these cell lines revealed aneuploidy, and the authenticity was confirmed by mitochondrial Cytochrome C Oxidase Subunit I (COI) genotyping analysis. Cell cycle studies were performed utilizing the flow cytometric technique. CA1F3Ex and CA1F4Tr cell lines showed high transfection efficiency with pEGFP-N1 plasmid using Lipofectamine and cytotoxicity towards heavy metals (Hg and Cd) was also studied. Hence, these continuous cell lines could be employed as in vitro models for aquatic toxicological and genetic manipulation studies.

Deactivation of LVAD support for myocardial recovery-surgical perspectives.

Left ventricular assist devices (LVADs) are excellent therapies for advanced heart failure patients either bridged to transplant or for lifetime use. LVADs also allow for reverse remodeling of the failing heart that is often associated with functional improvement. Indeed, growing enthusiasm exists to better understand this population of patients, whereby the LVAD is used as an adjunct to mediate myocardial recovery. When patients achieve benchmarks suggesting that they no longer need LVAD support, questions related to the discontinuation of LVAD therapy become front and center. The purpose of this review is to provide a surgical perspective on the practical and technical issues surrounding LVAD deactivation.

An in vitro nevus explant model for studying the effects of ultraviolet radiation.

Ultraviolet radiation (UVR) has been recognized as a potential trigger for the transformation of benign melanocytic nevi into melanoma. However, the mechanisms governing the formation and progression of melanocytic nevi remain poorly understood. This lack of understanding is partly due to the difficulty in isolating and culturing nevus tissues in vitro, resulting in a dearth of robust ex vivo models for nevi. Therefore, the establishment of a reliable melanocytic nevus model is imperative. Such a model is essential for elucidating nevus pathogenesis and facilitating the development of effective therapeutic interventions. Therefore, we have sought to establish an ex vivo nevus explant model to study UVR stimulation. And the structural integrity and tissue activity of the ex vivo nevi explant model was evaluated. We then observed melanogenesis and proliferation activity of the explants after UVR stimulation. There was less blister formation after Day 3 in nevi explants under our modified medium conditions. The nevi explant was able to maintain almost the same morphological structure and tissue activity as in vivo tissue within 24 h. Following UVR stimulation, we observed increased melanogenesis and proliferation activity in nevi explants. Nevi explants could serve as an ex vivo model for UVR-induced nevi stimulation research.

A Human Skin Explant Test as a Novel In Vitro Assay for the Detection of Skin Sensitization to Aggregated Monoclonal Antibodies.

Introduction: Monoclonal antibodies (mAbs) are important therapeutics. However, the enhanced potential for aggregation has become a critical quality parameter during the production of mAbs. Furthermore, mAb aggregation may also present a potential health risk in a clinical setting during the administration of mAb therapeutics to patients. While the extent of immunotoxicity in patient populations is uncertain, reports show it can lead to immune responses via cell activation and cytokine release. In this study, an autologous in vitro skin test designed to predict adverse immune events, including skin sensitization, was used as a novel assay for the assessment of immunotoxicity caused by mAb aggregation. Material and Methods: Aggregation of mAbs was induced by a heat stress protocol, followed by characterization of protein content by analytical ultra-centrifugation and transmission electron microscopy, revealing a 4% aggregation level of total protein content. Immunotoxicity and potential skin sensitization caused by the aggregates, were then tested in a skin explant assay. Results: Aggregated Herceptin and Rituximab caused skin sensitization, as shown by histopathological damage (grade II-III positive response) together with positive staining for Heat Shock Protein 70 (HSP70). Changes in T cell proliferation were not observed. Cytokine analysis revealed a significant increase of IL-10 for the most extreme condition of aggregation (65 °C at pH3) and a trend for an overall increase of IFN-γ, especially in response to Rituximab. Conclusions: The skin explant assay demonstrated that aggregated mAbs showed adverse immune reactions, as demonstrated as skin sensitization, with histopathological grades II-III. The assay may, therefore, be a novel tool for assessing immunotoxicity and skin sensitization caused by mAb aggregation.