Enumeration of CD4+ T-Cells Using a Portable Microchip Count Platform in Tanzanian HIV-Infected Patients

Abstract

BackgroundCD4+ T-lymphocyte count (CD4 count) is a standard method used to monitor HIV-infected patients during anti-retroviral therapy (ART). The World Health Organization (WHO) has pointed out or recommended that a handheld, point-of-care, reliable, and affordable CD4 count platform is urgently needed in resource-scarce settings.MethodsHIV-infected patient blood samples were tested at the point-of-care using a portable and label-free microchip CD4 count platform that we have developed. A total of 130 HIV-infected patient samples were collected that included 16 de-identified left over blood samples from Brigham and Women's Hospital (BWH), and 114 left over samples from Muhimbili University of Health and Allied Sciences (MUHAS) enrolled in the HIV and AIDS care and treatment centers in the City of Dar es Salaam, Tanzania. The two data groups from BWH and MUHAS were analyzed and compared to the commonly accepted CD4 count reference method (FACSCalibur system).ResultsThe portable, battery operated and microscope-free microchip platform developed in our laboratory (BWH) showed significant correlation in CD4 counts compared with FACSCalibur system both at BWH (r = 0.94, p<0.01) and MUHAS (r = 0.49, p<0.01), which was supported by the Bland-Altman methods comparison analysis. The device rapidly produced CD4 count within 10 minutes using an in-house developed automated cell counting program.ConclusionsWe obtained CD4 counts of HIV-infected patients using a portable platform which is an inexpensive (<$1 material cost) and disposable microchip that uses whole blood sample (<10 µl) without any pre-processing. The system operates without the need for antibody-based fluorescent labeling and expensive fluorescent illumination and microscope setup. This portable CD4 count platform displays agreement with the FACSCalibur results and has the potential to expand access to HIV and AIDS monitoring using fingerprick volume of whole blood and helping people who suffer from HIV and AIDS in resource-limited settings.

Simple filter microchip for rapid separation of plasma and viruses from whole blood

“…The device was fabricated utilizing a laser cutter, as previously described. 4,7,14,30,31 The device had outer dimensions of 25 × 40 mm. PMMA and DSA layer thicknesses were 1.5 mm and 50 µm, respectively.…”

“…As such, microfluidic systems, due to their portability, affordability, and high sensitivity, have become promising technologies to develop point-of-care (POC) diagnostics. [4][5][6][7] Currently, POC diagnostics require on-chip sample processing, including plasma separation from whole blood as an initial step. 8,9 For example, inclusion of blood cells or components such as hemoglobin and lactoferrin may inhibit DNA polymerase in polymerase chain reaction (PCR) analysis and lead to inaccurate quantification or even amplification failure.…”

Portable microfluidic chip for detection of Escherichia coli in produce and blood

“…18,24,25 The device was designed with dimensions of 22 mm × 60 mm with three parallel microchannels. To assemble this device, poly(methyl methacrylate) (PMMA) (1.5 mm thick; McMaster Carr, Atlanta, GA) and doublesided adhesive film (DSA) (50 µm thick; iTapestore, Scotch Plains, NJ) were cut using a laser cutter (Versa Laser™, Scottsdale, AZ).…”

“…The bacteria can be visualized either under a microscope in a laboratory setting, or for rapid counts in POC settings, with wide field of view lensless imaging systems for rapid counts for POC settings. 20,24,25,34 Also, for characterization of E. coli capture from various biological samples, we employed a GFPexpressing strain for ease of detection under a fluorescence microscope. The extension from a GFP-expressing strain to wild-type strains can be simply achieved using an ELISA-based detection method, as previously reported.…”

“…The extension from a GFP-expressing strain to wild-type strains can be simply achieved using an ELISA-based detection method, as previously reported. 35 The characterized microchip can be coupled with POC detection technologies such as surface plasmon resonance, [36][37][38] on-chip ELISA, 39 and lensless imaging 20,24 to achieve POC testing without reference to laboratory equipment. Additionally, the presented microfluidic approach can be adapted to detect other microorganisms that cause sepsis such as Gram-negative bacteria (E. coli, Klebsiella, Pseudomonas, Enterobacter, and Hemophilus species) and Gram-positive bacteria (Staphylococcus, Streptococcus, and Enterococcus species).…”