Mechanical segregation and capturing of clonal circulating plasma cells in multiple myeloma using micropillar-integrated microfluidic device

Utilizing 3D Models to Unravel the Dynamics of Myeloma Plasma Cells' Escape from the Bone Marrow Microenvironment

Recent therapeutic advancements have markedly increased the survival rates of individuals with multiple myeloma (MM), doubling survival compared to pre-2000 estimates. This progress, driven by highly effective novel agents, suggests a growing population of MM survivors exceeding the 10-year mark post-diagnosis. However, contemporary clinical observations indicate potential trends toward more aggressive relapse phenotypes, characterized by extramedullary disease and dominant proliferative clones, despite these highly effective treatments. To build upon these advances, it is crucial to develop models of MM evolution, particularly focusing on understanding the biological mechanisms behind its development outside the bone marrow. This comprehensive understanding is essential to devising innovative treatment strategies. This review emphasizes the role of 3D models, specifically addressing the bone marrow microenvironment and development of extramedullary sites. It explores the current state-of-the-art in MM modelling, highlighting challenges in replicating the disease's complexity. Recognizing the unique demand for accurate models, the discussion underscores the potential impact of these advanced 3D models on understanding and combating this heterogeneous and still incurable disease.

Label-free microfluidic chip for segregation and recovery of circulating leukemia cells: clinical applications in acute myeloid leukemia

We present a label-free microfluidic chip for the segregation of circulating leukemia cells (CLCs) from blood samples, with a focus on its clinical applications in Acute Myeloid Leukemia (AML). The microfluidic chip achieved an approximate capture efficiency of 92%. The study analyzed a comprehensive set of 66 blood specimens from AML patients in different disease stages, including newly diagnosed and relapsing cases, patients in complete remission, and those in partial remission. The results showed a significant difference in CLC counts between active disease stages and remission stages (p < 0.0001), with a proposed threshold of 5 CLCs to differentiate between the two. The microfluidic chip exhibited a sensitivity of 95.4% and specificity of 100% in predicting disease recurrence. Additionally, the captured CLCs were subjected to downstream molecular analysis using droplet digital PCR, allowing for the identification of genetic mutations associated with AML. Comparative analysis with bone marrow aspirate processing by FACS demonstrated the reliability and accuracy of the microfluidic chip in tracking disease burden, with highly agreement results obtained between the two methods. The non-invasive nature of the microfluidic chip and its ability to provide real-time insights into disease progression make it a promising tool for the proactive monitoring and personalized patient care of AML.

Precision Isolation of Circulating Leukemia Cells in Chronic Myelogenous Leukemia Patients Using a Novel Microfluidic Device and Its Clinical Applications

Chronic Myelogenous Leukemia (CML) is a prevalent hematologic malignancy characterized by the malignant transformation of myeloid cells and their proliferation in the peripheral blood. The management of CML poses significant challenges, particularly in detecting and eradicating minimal residual disease, which is crucial for preventing relapse and improving survival outcomes. Traditional minimal residual disease detection methods, such as bone marrow aspiration, are invasive and have limitations which include the potential for sampling errors and false negatives. This study introduces a novel label-free microfluidic chip designed for the segregation and recovery of circulating leukemia cells, offering a non-invasive liquid biopsy approach with potential applications in precision medicine. Over July 2021 to October 2023, we recruited 56 CML patients across various disease stages and collected blood samples for analysis using our microfluidic device. The device demonstrated high efficacy in isolating circulating leukemia cells, with an optimal capture efficiency of 78% at a sample flow rate of 3 mL/h. Our results indicate that the microfluidic device can efficiently segregate and quantify circulating leukemia cells, providing a detailed understanding of CML progression and treatment response. The significant reduction in circulating leukemia cell counts in patients in complete remission highlights the device's potential in monitoring treatment efficacy. Furthermore, the device's sensitivity in detecting minimal residual disease could offer a more reliable prognostic tool for therapeutic decision-making in CML management.

Review on Bortezomib Resistance in Multiple Myeloma and Potential Role of Emerging Technologies

Multiple myeloma is a hematological cancer type. For its treatment, Bortezomib has been widely used. However, drug resistance to this effective chemotherapeutic has been developed for various reasons. 2D cell cultures and animal models have failed to understand the MM disease and Bortezomib resistance. It is therefore essential to utilize new technologies to reveal a complete molecular profile of the disease. In this review, we in-depth examined the possible molecular mechanisms that cause Bortezomib resistance and specifically addressed MM and Bortezomib resistance. Moreover, we also included the use of nanoparticles, 3D culture methods, microfluidics, and organ-on-chip devices in multiple myeloma. We also discussed whether the emerging technology offers the necessary tools to understand and prevent Bortezomib resistance in multiple myeloma. Despite the ongoing research activities on MM, the related studies cannot provide a complete summary of MM. Nanoparticle and 3D culturing have been frequently used to understand MM disease and Bortezomib resistance. However, the number of microfluidic devices for this application is insufficient. By combining siRNA/miRNA technologies with microfluidic devices, a complete molecular genetic profile of MM disease could be revealed. Microfluidic chips should be used clinically in personal therapy and point-of-care applications. At least with Bortezomib microneedles, it could be ensured that MM patients can go through the treatment process more painlessly. This way, MM can be switched to the curable cancer type list, and Bortezomib can be targeted for its treatment with fewer side effects.

Stimulus-Responsive Microfluidic Interface Enables Efficient Enrichment and Cytogenetic Profiling of Circulating Myeloma Cells

Minimal residual disease (MRD) provides an independent prognostic factor for multiple myeloma (MM) patients. However, clinical MRD assays suffer from highly invasive sampling, insufficient detection sensitivity, and high cost. Herein, a stiMulus-Responsive ligand-Decorated microfluidic chip (MRD-Chip) was developed for efficient capture and controlled release of circulating myeloma cells (CMCs) in the peripheral blood for noninvasive myeloma evaluation. The CD138 antibody-decorated herringbone chip with a disulfide linker was designed to enhance the collision probability between blood cells and capture antibodies, leading to high capture efficiency of CMCs. More importantly, the captured CMCs can be nondestructively released via a thiol-exchange reaction, allowing them to be used for subsequent cellular and molecular analysis. By fluorescence in situ hybridization assay, we successfully identified the cytogenetic abnormalities (chromosome 1q21 amplification and p53 deletion) of CMCs in clinical samples. Overall, with the merits of noninvasive sampling, high capture efficiency (70.93%), high throughput (1.5 mL/h), and nondestructive release of target cells (over 90% viability) for downstream analysis, our strategy provides new opportunities for myeloma evaluation, such as prognosis assessment, efficacy monitoring, and mechanism research of disease relapse and drug resistance.

Optimization of PTFE Coating on PDMS Surfaces for Inhibition of Hydrophobic Molecule Absorption for Increased Optical Detection Sensitivity

Polydimethylsiloxane (PDMS) is a polymer widely used for fabrication and prototyping of microfluidic chips. The porous matrix structure of PDMS allows small hydrophobic molecules including some fluorescent dyes to be readily absorbed to PDMS and results in high fluorescent background signals, thereby significantly decreasing the optical detection sensitivity. This makes it challenging to accurately detect the fluorescent signals from samples using PDMS devices. Here, we have utilized polytetrafluoroethylene (PTFE) to inhibit absorption of hydrophobic small molecules on PDMS. Nile red was used to analyze the effectiveness of the inhibition and the absorbed fluorescence intensities for 3% and 6% PTFE coating (7.7 ± 1.0 and 6.6 ± 0.2) was twofold lower compared to 1% and 2% PTFE coating results (17.2 ± 0.5 and 15.4 ± 0.5). When compared to the control (55.3 ± 1.6), it was sevenfold lower in background fluorescent intensity. Furthermore, we validated the optimized PTFE coating condition using a PDMS bioreactor capable of locally stimulating cells during culture to quantitatively analyze the lipid production using Chlamydomonas reinhardtii CC-125. Three percent PTFE coating was selected as the optimal concentration as there was no significant difference between 3% and 6% PTFE coating. Intracellular lipid contents of the cells were successfully stained with Nile Red inside the bioreactor and 3% PTFE coating successfully minimized the background fluorescence noise, allowing strong optical lipid signal to be detected within the PDMS bioreactor comparable to that of off-chip, less than 1% difference.