Establishing mesothelioma patient-derived organoid models from malignant pleural effusions.

OBJECTIVES: Pleural mesothelioma is a cancer arising in the cells that line the lungs and chest wall with poor survival and poor response to first-line therapy. Organoid models of cancer can faithfully recapitulate the genetic and histopathological characteristics of individualized tumors and have potential to be used for precision medicine, however methods of establishing patient-derived mesothelioma organoids have not been well established in the published literature. MATERIALS AND METHODS: Long-term mesothelioma patient-derived organoids were established from ten malignant pleural effusion fluids. Mesothelioma patient-derived organoids were compared to the corresponding biopsy tissue specimens using immunohistochemistry labelling for select diagnostic markers and the TruSight Oncology-500 sequencing assay. Cell viability in response to the chemotherapeutic drug cisplatin was assessed. RESULTS: We established five mesothelioma patient-derived organoid cultures from ten malignant pleural effusion fluids collected from nine individuals with pleural mesothelioma. Mesothelioma patient-derived organoids typically reflected the histopathological and genomic features of patients' matched biopsy specimens and displayed cytotoxic sensitivity to cisplatin in vitro. CONCLUSION: This is the first study of its kind to establish long-term mesothelioma organoid cultures from malignant pleural effusions and report on their utility to test individuals' chemotherapeutic sensitivities ex vivo.

An Anti-VEGF-B Antibody Fragment Induces Regression of Pre-Existing Blood Vessels in the Rat Cornea.

Purpose: We tested the ability of an antibody fragment with specificity for vascular endothelial growth factor-B (VEGF-B) to regress nascent and established corneal blood vessels in the rat. Methods: A single chain variable antibody fragment (scFv) with specificity for VEGF-B was engineered from the 2H10 hybridoma. Binding to rat, mouse, and human VEGF-B was confirmed by surface plasmon resonance. Activity of the anti-VEGF-B scFv on developing and established corneal blood vessels was assessed following unilateral superficial cautery in male and female outbred Sprague Dawley rats. Groups (untreated, control scFv-treated, or anti-VEGF-B scFv-treated) comprised 6 to 22 rats. Treatment consisted of 5 µL scFv, 1 mg/mL, applied topically five times per day for 14 days, or two subconjunctival injections, 50 µg scFv each, applied 7 days apart, or combined topical and subconjunctival treatment. Corneal vessel area was quantified on hematoxylin-stained corneal flat-mounts, and groups were compared using the Mann-Whitney U test, with post hoc Bonferroni correction. Immunohistochemistry for cleaved caspase-3 was performed. Results: Topical anti-VEGF-B scFv therapy alone did not regress corneal blood vessels significantly (P > 0.05). Subconjunctival injection and combined treatment regressed 14-day established corneal blood vessels (25% reduction in vessel area [P = 0.04] and 37% reduction in vessel area [P < 0.001], respectively, compared to results in untreated controls). Cleaved caspase-3 was identified in vascular endothelial cells of anti-VEGF-B scFv-treated corneas. In scFv-treated rats, corneal endothelial cell function was maintained to 12 weeks after treatment and a normal blink reflex was present. Conclusions: The anti-VEGF-B scFv significantly regressed established but not developing corneal blood vessels in rats.

Interleukin-10 Gene Transfer in Rat Limbal Transplantation.

PURPOSE: To evaluate the gene transfer of the interleukin (IL)-10 cytokine as a treatment modality for prolonging limbal allograft survival in a rat model. MATERIALS AND METHODS: Adenoviral (AV) and lentiviral (LV) vectors were produced for ex vivo gene transfer into limbal graft tissue prior to orthotopic transplantation. Experimental groups comprised unmodified isografts, unmodified allografts, allografts transfected with a reporter gene, and allografts transfected with IL-10. The functional effects of the transgenes were determined by clinical assessment and by following donor cell survival in the recipient animal. Group comparisons were made using survival analysis and tested with the log-rank test. Differences in mean rejection times between groups were tested using the Wilcoxon rank-sum test. RESULTS: Isografts survived during the entire observation period of 56 days. Allografts underwent clinical rejection at a mean of 6.7 days (standard deviation 2.0) postoperatively, irrespective of the presence of transgenes (p < 0.001 for difference in rejection times). For both the AV and LV vector systems, Kaplan-Meier analysis showed a statistically significant difference with respect to time-to-graft failure when comparing allografts transfected with IL-10 with allografts transfected with reporter gene alone (p = 0.011 and p < 0.001, respectively). In the isografts, donor cells could be detected during the complete observation period. In all the allograft groups, however, donor cell detection declined after 1 week and was lost after 4 weeks. CONCLUSIONS: Under the conditions tested in the present model, both the AV and the LV vector systems were able to transfect limbal graft tissue ex vivo with biologically active IL-10, leading to delayed rejection compared to the controls.

Co-expression of a scFv antibody fragment and a reporter protein using lentiviral shuttle plasmid containing a self-processing furin-2A sequence.

It is often desirable to co-express a reporter protein with a potential therapeutic protein, to verify correct targeting of an expression strategy. Vectors containing a viral self-processing 2A sequence have been reported to drive equimolar expression of two or more transgenes from a single promoter. Here, we report on the co-expression of a secreted antibody fragment and an intracellular reporter protein, enhanced yellow fluorescent protein from lentiviral shuttle plasmids by inserting a furin-2A (F2A) sequence between the two cDNAs, in two different orientations, in the expression cassette. We show that the order of these two transgenes relative to the F2A sequence affects expression levels. Reduced expression of each transgene positioned downstream of F2A, compared with upstream of F2A, was observed (p<0.05). Moreover, protein expression from double-cDNA plasmids was significantly lower than from their corresponding single transgene counterparts (p<0.05).

Expression of an anti-CD4 single-chain antibody fragment from the donor cornea can prolong corneal allograft survival in inbred rats.

AIM: To investigate whether expression of an anti-CD4 antibody fragment (scFv) by a lentivector-transduced donor cornea can prolong rat corneal allograft survival. METHODS: Inbred Fischer 344 rats received penetrating corneal allografts from Wistar-Furth donors after a 3 h transduction of the donor cornea with a lentivector carrying anti-CD4scFv cDNA (Lv-CD4scFv), a lentivector carrying the reporter gene-enhanced yellow fluorescence protein (LV-eYFP), or an adenoviral vector carrying anti-CD4 scFv cDNA (Ad-CD4scFv). Unmodified controls were also performed. Graft survival was assessed by corneal clarity, and rejection was confirmed histologically. RESULTS: In organ-cultured corneas, expression of anti-CD4 scFv was detected at 2 days post-transduction with the adenoviral vector, compared with 5 days post-transduction with the lentivector, and was 10-fold higher than the former. More inflammation was observed in Ad-CD4scFv-modified allografts than in Lv-CD4scFv-modified grafts at 15 days postsurgery (p=0.01). The median time to rejection for unmodified, LV-eYFP and Ad-CD4scFv grafts was day 17, compared with day 22 for Lv-CD4scFv grafts (p≤0.018). CONCLUSION: Donor corneas transduced with a lentiviral vector carrying anti-CD4scFv cDNA showed a modest but significant prolongation in graft survival compared with unmodified, Lv-eYFP and Ad-CD4scFv grafts. However, rejection still occurred in all Lv-CD4scFv grafts, indicating that sensitisation may have been delayed but was not prevented.