Antibody dependent cellular cytotoxicity-inducing anti-EGFR antibodies as effective therapeutic option for cutaneous melanoma resistant to BRAF inhibitors.

Introduction: About 50% of cutaneous melanoma (CM) patients present activating BRAF mutations that can be effectively targeted by BRAF inhibitors (BRAFi). However, 20% of CM patients exhibit intrinsic drug resistance to BRAFi, while most of the others develop adaptive resistance over time. The mechanisms involved in BRAFi resistance are disparate and globally seem to rewire the cellular signaling profile by up-regulating different receptor tyrosine kinases (RTKs), such as the epidermal growth factor receptor (EGFR). RTKs inhibitors have not clearly demonstrated anti-tumor activity in BRAFi resistant models. To overcome this issue, we wondered whether the shared up-regulated RTK phenotype associated with BRAFi resistance could be exploited by using immune weapons as the antibody-dependent cell cytotoxicity (ADCC)-mediated effect of anti-RTKs antibodies, and kill tumor cells independently from the mechanistic roots. Methods and results: By using an in vitro model of BRAFi resistance, we detected increased membrane expression of EGFR, both at mRNA and protein level in 4 out of 9 BRAFi-resistant (VR) CM cultures as compared to their parental sensitive cells. Increased EGFR phosphorylation and AKT activation were observed in the VR CM cultures. EGFR signaling appeared dispensable for maintaining resistance, since small molecule-, antibody- and CRISPR-targeting of EGFR did not restore sensitivity of VR cells to BRAFi. Importantly, immune-targeting of EGFR by the anti-EGFR antibody cetuximab efficiently and specifically killed EGFR-expressing VR CM cells, both in vitro and in humanized mouse models in vivo, triggering ADCC by healthy donors' and patients' peripheral blood cells. Conclusion: Our data demonstrate the efficacy of immune targeting of RTKs expressed by CM relapsing on BRAFi, providing the proof-of-concept supporting the assessment of anti-RTK antibodies in combination therapies in this setting. This strategy might be expected to concomitantly trigger the crosstalk of adaptive immune response leading to a complementing T cell immune rejection of tumors.

Autophagy in BRAF-mutant cutaneous melanoma: recent advances and therapeutic perspective.

Macroautophagy, hereafter referred to as autophagy, represents a highly conserved catabolic process that maintains cellular homeostasis. At present, the role of autophagy in cutaneous melanoma (CM) is still controversial, since it appears to be tumor-suppressive at early stages of malignant transformation and cancer-promoting during disease progression. Interestingly, autophagy has been found to be often increased in CM harboring BRAF mutation and to impair the response to targeted therapy. In addition to autophagy, numerous studies have recently conducted in cancer to elucidate the molecular mechanisms of mitophagy, a selective form of mitochondria autophagy, and secretory autophagy, a process that facilitates unconventional cellular secretion. Although several aspects of mitophagy and secretory autophagy have been investigated in depth, their involvement in BRAF-mutant CM biology has only recently emerged. In this review, we aim to overview autophagy dysregulation in BRAF-mutant CM, along with the therapeutic advantages that may arise from combining autophagy inhibitors with targeted therapy. In addition, the recent advances on mitophagy and secretory autophagy involvement in BRAF-mutant CM will be also discussed. Finally, since a number of autophagy-related non-coding RNAs (ncRNAs) have been identified so far, we will briefly discussed recent advances linking ncRNAs to autophagy regulation in BRAF-mutant CM.

LINE-1 hypomethylation is associated with poor outcomes in locoregionally advanced oropharyngeal cancer.

BACKGROUND AND PURPOSE: Currently, human papillomavirus (HPV) positivity represents a strong prognostic factor for both reduced risk of relapse and improved survival in patients with oropharyngeal squamous cell carcinoma (OPSCC). However, a subset of HPV-positive OPSCC patients still experience poor outcomes. Furthermore, HPV-negative OPSCC patients, who have an even higher risk of relapse, are still lacking suitable prognostic biomarkers for clinical outcome. Here, we evaluated the prognostic value of LINE-1 methylation level in OPSCC patients and further addressed the relationship between LINE-1 methylation status and p53 protein expression as well as genome-wide/gene-specific DNA methylation. RESULTS: In this study, DNA was extracted from 163 formalin-fixed paraffin-embedded tissue samples retrospectively collected from stage III-IVB OPSCC patients managed with curative intent with up-front treatment. Quantitative methylation-specific PCR revealed that LINE-1 hypomethylation was directly associated with poor prognosis (5-year overall survival-OS: 28.1% for LINE-1 methylation < 35% vs. 69.1% for ≥ 55%; p < 0.0001). When LINE-1 methylation was dichotomized as < 55% versus ≥ 55%, interaction with HPV16 emerged: compared with hypermethylated HPV16-positive patients, subjects with hypomethylated HPV16-negative OPSCC reported an adjusted higher risk of death (HR 4.83, 95% CI 2.24-10.38) and progression (HR 4.54, 95% CI 2.18-9.48). Tumor protein p53 (TP53) gene is often mutated and overexpressed in HPV-negative OPSCC. Since p53 has been reported to repress LINE-1 promoter, we then analyzed the association between p53 protein expression and LINE-1 methylation levels. Following p53 immunohistochemistry, results indicated that among HPV16-negative patients with p53 ≥ 50%, LINE-1 methylation levels declined and remained stable at approximately 43%; any HPV16-positive patient reported p53 ≥ 50%. Finally, DNA methylation analysis demonstrated that genome-wide average methylation level at cytosine-phosphate-guanine sites was significantly lower in HPV16-negative OPSCC patients who relapsed within two years. The subsequent integrative analysis of gene expression and DNA methylation identified 20 up-regulated/hypomethylated genes in relapsed patients, and most of them contained LINE-1 elements in their promoter sequences. CONCLUSIONS: Evaluation of the methylation level of LINE-1 may help in identifying the subset of OPSCC patients with bad prognosis regardless of their HPV status. Aberrant LINE-1 hypomethylation might occur along with TP53 mutations and lead to altered gene expression in OPSCC.

Prognostic Significance of PD-L1 Expression In Patients With Primary Oropharyngeal Squamous Cell Carcinoma: A Meta-Analysis.

BACKGROUND: At present, the prognostic significance of programmed cell death receptor ligand 1 (PD-L1) expression in oropharyngeal squamous cell carcinoma (OPSCC) patients is still controversial. In this study, we aim to synthesize relevant studies that have assessed the prognostic value of PD-L1 in patients with primary OPSCC treated according to the current standard-of-care. METHODS: A systematic search of Medline/PubMed, Cochrane, Embase, Web of Science, and Scopus was conducted to define the prognostic role of PD-L1 expression in OPSCC. All studies published before July 31, 2021 were screened. Summary hazard ratios (sHR) with 95% confidence intervals (CIs) were calculated using a random-effects model. RESULTS: A total of 1522 OPSCC patients from 12 studies were included. PD-L1 expression in OPSCC tumor cells (TCs) was significantly associated with longer overall survival (sHR=0.63, 95% CI 0.50-0.79), and progression-free survival (sHR=0.62, 95% CI 0.49-0.79). A benefit in survival was also observed in PD-L1-positive OPSCC patients who underwent surgery (sHR=0.34, 95% CI 0.18-0.65). Finally, although PD-L1-positive expression was related to better outcomes both in HPV-negative and HPV-positive OPSCC, the difference reached the statistical significance only in the HPV-positive subgroup (sHR=0.37, 95% CI 0.19-0.73). No heterogeneity emerged between studies for all considered outcomes, with I 2 ranging from 0% for progression-free survival to 11% for overall survival. CONCLUSIONS: PD-L1 expression on TCs associated with improved survival in OPSCC. In particular, HPV-positive OPSCC most benefited from PD-L1 expression when compared to the PD-L1 negative counterpart. Thus, PD-L1 might represent a useful biomarker to stratify prognosis in OPSCC in addition to HPV status.

Prognostic Nutritional Index Predicts Toxicity in Head and Neck Cancer Patients Treated with Definitive Radiotherapy in Association with Chemotherapy.

BACKGROUND: The Prognostic Nutritional Index (PNI) is a parameter of nutritional and inflammation status related to toxicity in cancer treatment. Since data for head and neck cancer are scanty, this study aims to investigate the association between PNI and acute and late toxicity for this malignancy. METHODS: A retrospective cohort of 179 head and neck cancer patients treated with definitive radiotherapy with induction/concurrent chemotherapy was followed-up (median follow-up: 38 months) for toxicity and vital status between 2010 and 2017. PNI was calculated according to Onodera formula and low/high PNI levels were defined according to median value. Odds ratio (OR) for acute toxicity were calculated through logistic regression model; hazard ratios (HR) for late toxicity and survival were calculated through the Cox proportional hazards model. RESULTS: median PNI was 50.0 (interquartile range: 45.5-53.5). Low PNI was associated with higher risk of weight loss > 10% during treatment (OR = 4.84, 95% CI: 1.73-13.53 for PNI < 50 versus PNI ≥ 50), which was in turn significantly associated with worse overall survival, and higher risk of late mucositis (HR = 1.84; 95% CI:1.09-3.12). PNI predicts acute weight loss >10% and late mucositis. CONCLUSIONS: PNI could help clinicians to identify patients undergoing radiotherapy who are at high risk of acute and late toxicity.

Long Noncoding RNAs as Innovative Urinary Diagnostic Biomarkers.

The characterization of circulating tumor cells (CTCs) is now widely studied as a promising source of cancer-derived biomarkers because of their role in tumor formation and progression. However, CTCs analysis presents some limitations and no standardized method for CTCs isolation from urine has been defined so far. In fact, besides blood, urine represents an ideal source of noninvasive biomarkers, especially for the early detection of genitourinary tumors. Besides CTCs, long noncoding RNAs (lncRNAs) have also been proposed as potential noninvasive biomarkers, and the evaluation of the diagnostic accuracy of urinary lncRNAs has dramatically increased over the last years, with many studies being published. Therefore, this review provides an update on the clinical utility of urinary lncRNAs as novel biomarkers for the diagnosis of bladder and prostate cancers.

Beyond MicroRNAs: Emerging Role of Other Non-Coding RNAs in HPV-Driven Cancers.

Persistent infection with high-risk Human Papilloma Virus (HPV) leads to the development of several tumors, including cervical, oropharyngeal, and anogenital squamous cell carcinoma. In the last years, the use of high-throughput sequencing technologies has revealed a number of non-coding RNA (ncRNAs), distinct from micro RNAs (miRNAs), that are deregulated in HPV-driven cancers, thus suggesting that HPV infection may affect their expression. However, since the knowledge of ncRNAs is still limited, a better understanding of ncRNAs biology, biogenesis, and function may be challenging for improving the diagnosis of HPV infection or progression, and for monitoring the response to therapy of patients affected by HPV-driven tumors. In addition, to establish a ncRNAs expression profile may be instrumental for developing more effective therapeutic strategies for the treatment of HPV-associated lesions and cancers. Therefore, this review will address novel classes of ncRNAs that have recently started to draw increasing attention in HPV-driven tumors, with a particular focus on ncRNAs that have been identified as a direct target of HPV oncoproteins.

Publisher Correction: Innovative mouse model mimicking human-like features of spinal cord injury: efficacy of Docosahexaenoic acid on acute and chronic phases.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Innovative mouse model mimicking human-like features of spinal cord injury: efficacy of Docosahexaenoic acid on acute and chronic phases.

Traumatic spinal cord injury has dramatic consequences and a huge social impact. We propose a new mouse model of spinal trauma that induces a complete paralysis of hindlimbs, still observable 30 days after injury. The contusion, performed without laminectomy and deriving from the pressure exerted directly on the bone, mimics more closely many features of spinal injury in humans. Spinal cord was injured at thoracic level 10 (T10) in adult anesthetized female CD1 mice, mounted on stereotaxic apparatus and connected to a precision impactor device. Following severe injury, we evaluated motor and sensory functions, and histological/morphological features of spinal tissue at different time points. Moreover, we studied the effects of early and subchronic administration of Docosahexaenoic acid, investigating functional responses, structural changes proximal and distal to the lesion in primary and secondary injury phases, proteome modulation in injured spinal cord. Docosahexaenoic acid was able i) to restore behavioural responses and ii) to induce pro-regenerative effects and neuroprotective action against demyelination, apoptosis and neuroinflammation. Considering the urgent health challenge represented by spinal injury, this new and reliable mouse model together with the positive effects of docosahexaenoic acid provide important translational implications for promising therapeutic approaches for spinal cord injuries.

Creamino: A Cost-Effective, Open-Source EEG-Based BCI System.

This paper presents an open source framework called Creamino. It consists of an Arduino-based cost-effective quick-setup EEG platform built with off-the-shelf components and a set of software modules that easily allow users to connect this system to Simulink or BCI-oriented tools (such as BCI2000 or OpenViBE) and set up a wide number of neuroscientific experiments. Creamino is capable of processing multiple EEG channels in real-time and operates under Windows, Linux, and Mac OS X in real-time on a standard PC. Its objective is to provide a system that can be readily fabricated and used for neurophysiological experiments and, at the same time, can serve as the basis for development of novel BCI platforms by accessing and modifying its open source hardware and software libraries. Schematics, gerber files, bill of materials, source code, software modules, demonstration videos, and instructions on how to use these modules are available free of charge for research and educational purposes online at https://github.com/ArcesUnibo/creamino. Application cases show how the system can be used for neuroscientific or BCI experiments. Thanks to its low production cost and its compatibility with open-source BCI tools, the system presented is particularly suitable for use in BCI research and educational applications.

Parallel Solver for Diffuse Optical Tomography on Realistic Head Models With Scattering and Clear Regions.

Diffuse optical tomography is an imaging technique, based on evaluation of how light propagates within the human head to obtain the functional information about the brain. Precision in reconstructing such an optical properties map is highly affected by the accuracy of the light propagation model implemented, which needs to take into account the presence of clear and scattering tissues. We present a numerical solver based on the radiosity-diffusion model, integrating the anatomical information provided by a structural MRI. The solver is designed to run on parallel heterogeneous platforms based on multiple GPUs and CPUs. We demonstrate how the solver provides a 7 times speed-up over an isotropic-scattered parallel Monte Carlo engine based on a radiative transport equation for a domain composed of 2 million voxels, along with a significant improvement in accuracy. The speed-up greatly increases for larger domains, allowing us to compute the light distribution of a full human head ( ≈ 3 million voxels) in 116 s for the platform used.

A Driving Right Leg Circuit (DgRL) for Improved Common Mode Rejection in Bio-Potential Acquisition Systems.

The paper presents a novel Driving Right Leg (DgRL) circuit designed to mitigate the effect of common mode signals deriving, say, from power line interferences. The DgRL drives the isolated ground of the instrumentation towards a voltage which is fixed with respect to the common mode potential on the subject, therefore minimizing common mode voltage at the input of the front-end. The paper provides an analytical derivation of the common mode rejection performances of DgRL as compared to the usual grounding circuit or Driven Right Leg (DRL) loop. DgRL is integrated in a bio-potential acquisition system to show how it can reduce the common mode signal of more than 70 dB with respect to standard patient grounding. This value is at least 30 dB higher than the reduction achievable with DRL, making DgRL suitable for single-ended front-ends, like those based on active electrodes. EEG signal acquisition is performed to show how the system can successfully cancel power line interference without any need for differential acquisition, signal post-processing or filtering.

Sub-apoptotic dosages of pro-oxidant vitamin cocktails sensitize human melanoma cells to NK cell lysis.

Alpha-tocopheryl succinate (αTOS), vitamin K3 (VK3) and vitamin C (ascorbic acid, AA) were previously shown to synergistically promote different death pathways in carcinoma cells, depending on their concentrations and combinations. Similar effects were observed herein in melanoma cells, although αTOS behaved as an antagonist. Interestingly, suboptimal cell death-inducing concentrations (1.5 µM αTOS/20 µM AA/0.2 µM VK3) effectively up-regulated activating Natural Killer (NK) cell ligands, including MICA (the stress-signaling ligand of the NKG2D receptor), and/or the ligands of at least one of the natural cytotoxicity receptors (NKp30, NKp44 and NKp46) in 5/6 melanoma cell lines. Only an isolated MICA down-regulation was seen. HLA class I, HLA class II, ULBP1, ULBP2, ULBP3, Nectin-2, and PVR displayed little, if any, change in expression. Ligand up-regulation resulted in improved lysis by polyclonal NK cells armed with the corresponding activating receptors. These results provide the first evidence for concerted induction of cell death by cell-autonomous and extrinsic (immune) mechanisms. Alarming the immune system much below the cell damage threshold may have evolved as a sensitive readout of neoplastic transformation and oxidative stress. Cocktails of vitamin analogues at slightly supra-physiological dosages may find application as mild complements of melanoma treatment, and in chemoprevention.

EEG acquisition system based on active electrodes with common-mode interference suppression by Driving Right Leg circuit.

We present a system for the acquisition of EEG signals based on active electrodes and implementing a Driving Right Leg circuit (DgRL). DgRL allows for single-ended amplification and analog-to-digital conversion, still guaranteeing a common mode rejection in excess of 110 dB. This allows the system to acquire high-quality EEG signals essentially removing network interference for both wet and dry-contact electrodes. The front-end amplification stage is integrated on the electrode, minimizing the system's sensitivity to electrode contact quality, cable movement and common mode interference. The A/D conversion stage can be either integrated in the remote back-end or placed on the head as well, allowing for an all-digital communication to the back-end. Noise integrated in the band from 0.5 to 100 Hz is comprised between 0.62 and 1.3 µV, depending on the configuration. Current consumption for the amplification and A/D conversion of one channel is 390 µA. Thanks to its low noise, the high level of interference suppression and its quick setup capabilities, the system is particularly suitable for use outside clinical environments, such as in home care, brain-computer interfaces or consumer-oriented applications.

Active electrode IC for EEG and electrical impedance tomography with continuous monitoring of contact impedance.

The IC presented integrates the front-end for EEG and Electrical Impedance Tomography (EIT) acquisition on the electrode, together with electrode-skin contact impedance monitoring and EIT current generation, so as to improve signal quality and integration of the two techniques for brain imaging applications. The electrode size is less than 2 cm(2) and only 4 wires connect the electrode to the back-end. The readout circuit is based on a Differential Difference Amplifier and performs single-ended amplification and frequency division multiplexing of the three signals that are sent to the back-end on a single wire which also provides power supply. Since the system's CMRR is a function of each electrode's gain accuracy, an analysis is performed on how this is influenced by mismatches in passive and active components. The circuit is fabricated in 0.35 µm CMOS process and occupies 4 mm(2), the readout circuit consumes 360 µW, the input referred noise for bipolar EEG signal acquisition is 0.56 µVRMS between 0.5 and 100 Hz and almost halves if only EEG signal is acquired.

Lysis-on-chip of single target cells following forced interaction with CTLs or NK cells on a dielectrophoresis-based array.

Guiding the interaction of single cells acting as partners in heterotypic interactions (e.g., effectors and targets of immune lysis) and monitoring the outcome of these interactions are regarded as crucial biomedical achievements. In this study, taking advantage of a dielectrophoresis (DEP)-based Laboratory-on-a-chip platform (the DEPArray), we show that it is possible to generate closed DEP cages entrapping CTLs and NK cells as either single cells or clusters; reversibly immobilize a single virus-presenting or tumor cell within the chip at a selected position; move cages and their content to predetermined spatial coordinates by software-guided routing; force a cytotoxic effector to physically interact with a putative target within a secluded area by merging their respective cages; generate cages containing effector and target cells at predetermined E:T ratios; accurately assess cytotoxicity by real-time quantitation of the release kinetics of the fluorescent dye calcein from target cells (>50 lytic events may be tested simultaneously); estimate end points of calcein release within 16 min of initial E:T cell contact; simultaneously deliver Ab-based phenotyping and on-chip lysis assessment; and identify lytic and nonlytic E:T combinations and discriminate nonlytic effector phenotypes from target refractoriness to immune lysis. The proof of principle is provided that DEPArray technology, previously used to levitate and move single cells, can be used to identify highly lytic antiviral CTLs and tumor cells that are particularly refractory to NK cell lysis. These findings are of primary interest in targeted immunotherapy.

Programmable interactions of functionalized single bioparticles in a dielectrophoresis-based microarray chip.

Manipulating single biological objects is a major unmet challenge of biomedicine. Herein, we describe a lab-on-a-chip platform based on dielectrophoresis (DEP). The DEParray is a prototypal version consisting of 320 × 320 arrayed electrodes generating >10,000 spherical DEP cages. It allows the capture and software-guided movement to predetermined spatial coordinates of single biological objects. With the DEParray we demonstrate (a) forced interaction between a single, preselected target cell and a programmable number of either microspheres or natural killer (NK) cells, (b) on-chip immunophenotypic discrimination of individual cells based on differential rosetting with microspheres functionalized with monoclonal antibodies to an inhibitory NK cell ligand (HLA-G), (c) on-chip, real-time (few minutes) assessment of immune lysis by either visual inspection or semiautomated, time-lapse reading of a fluorescent dye released from NK cell-sensitive targets, and (d) manipulation and immunophenotyping with limiting amounts (about 500) cells. To our knowledge, this is the first report describing a DEP-based lab-on-a-chip platform for the quick, arrayed, software-guided binding of individually moved biological objects, the targeting of single cells with microspheres, and the real-time characterization of immunophenotypes. The DEParray candidates as a discovery tool for novel cell:cell interactions with no prior (immuno)phenotypic knowledge.

High yield patterning of single cells from extremely small populations.

Many biological assays require the ability to isolate and process single cells. Some research fields, such as the characterization of rare cells, the in vitro processing of stem cells, and the study of early stage cell differentiation, call for the additional and typically unmet ability to work with extremely low-count cell populations. In all these cases, efficient single-cell handling must be matched with the ability to work on a limited number of cells with a low cell loss rate. In this paper, we present a platform combining flow-through processing with deterministic (nonstatistical) patterning of cells coming from extremely small cell populations. We describe here modules using dielectrophoresis to control the position of cells flowing in microchannels and to pattern them in open microwells where cells were further analyzed. K562 cells continuously flowing at a speed of up to 100 µm/s were tridimensionally focused, aligned, and patterned inside microwells. A high-patterning yield and low cell loss rate were demonstrated experimentally: 15uL drops, containing an average of 15 cells, were transferred to the microchannel with an 83% yield, and cells were then patterned into microwells with a 100% yield. The deterministic patterning of cells was demonstrated both by isolating single cells in microwells and by creating clusters composed of a predetermined number of cells. Cell proliferation was assessed by easily recovering cells from open microwells, and a growth rate comparable to the control was obtained.

Alpha-tocopheryl succinate inhibits autophagic survival of prostate cancer cells induced by vitamin K3 and ascorbate to trigger cell death.

BACKGROUND: The redox-silent vitamin E analog α-tocopheryl succinate (α-TOS) was found to synergistically cooperate with vitamin K3 (VK3) plus ascorbic acid (AA) in the induction of cancer cell-selective apoptosis via a caspase-independent pathway. Here we investigated the molecular mechanism(s) underlying cell death induced in prostate cancer cells by α-TOS, VK3 and AA, and the potential use of targeted drug combination in the treatment of prostate cancer. METHODOLOGY/PRINCIPAL FINDINGS: The generation of ROS, cellular response to oxidative stress, and autophagy were investigated in PC3 prostate cancer cells by using drugs at sub-toxic doses. We evaluated whether PARP1-mediated apoptosis-inducing factor (AIF) release plays a role in apoptosis induced by the combination of the agents. Next, the effect of the combination of α-TOS, VK3 and AA on tumor growth was examined in nude mice. VK3 plus AA induced early ROS formation associated with induction of autophagy in response to oxidative stress, which was reduced by α-TOS, preventing the formation of autophagosomes. α-TOS induced mitochondrial destabilization leading to the release of AIF. Translocation of AIF from mitochondria to the nucleus, a result of the combinatorial treatment, was mediated by PARP1 activation. The inhibition of AIF as well as of PARP1 efficiently attenuated apoptosis triggered by the drug combination. Using a mouse model of prostate cancer, the combination of α-TOS, VK3 and AA was more efficient in tumor suppression than when the drugs were given separately, without deleterious side effects. CONCLUSIONS/SIGNIFICANCE: α-TOS, a mitochondria-targeting apoptotic agent, switches at sub-apoptotic doses from autophagy-dependent survival of cancer cells to their demise by promoting the induction of apoptosis. Given the grim prognosis for cancer patients, this finding is of potential clinical relevance.

Inverted open microwells for cell trapping, cell aggregate formation and parallel recovery of live cells.

The inverted open microwell is a novel microstructure supporting isolation and trapping of cells, analysis of cell-cell and cell-molecule interactions and functional cell sorting. This work introduces the inverted open microwell concept, demonstrating successful isolation of K562 cells in 75 µm microwells fabricated on a flexible printed circuit board substrate, and recovery of viable cells onto standard microtiter plates after analysis and manipulation. Dielectrophoresis (DEP) was used during the delivery phase to control cell access to the microwell and force the formation of cell aggregates so as to ensure cell-cell contact and interaction. Cells were trapped at the air-fluid interface at the bottom edge of the open microwell. Once trapped, cells were retained on the meniscus even after DEP de-activation and fluid was exchanged to enable perfusion of nutrients and delivery of molecules to the microwell, as demonstrated by a calcein-staining protocol performed in the microsystem. Finally, cell viability was assessed on trapped cells by a calcein release assay and cell proliferation was demonstrated after multiple cells had been recovered in parallel onto standard microtiter plates.