Application and utility of alternative methods in isolation of pure cells from forensic biological mixtures in modern-day: a review

Abstract

Development of genetic profiles from the biological mixtures has remained challenging, although modern-day technologies may help forensic scientists to attain a reliable genetic profile in the identification of the accused. In the case of rape, vaginal swab exhibits usually contain epithelial cells of victims and sperm cells of accused, such samples are more challenging when there is more than one contributor. In such cases, separation of distinct cells from a mixture that includes blood cells, epithelial cells and sperm cells for their single genetic profile is important. In the last ten decades several new techniques were developed and invented for the separation of single cell from the biological mixture that includes differential lysis, laser micro-dissection, cell sorting (FACS), sieve-based filtration, (vi) micro-fluidic devices or immunomagnetic beads cell separation of fresh samples, and the magnetic activated cell sorting (MACS). Out of them, some techniques have been commonly applied for cell separation in forensic biology. Each technique has its own limitation. Some recent studies showed, magnetic activated cell sorting (MACS), laser capture microdissection (LCM), DEPArray technology and fluorescence activated cell sorting (FACS) has proved to be effective in separation of single cell from cell mixtures. Therefore, in this review we have evaluated these four alternative methods and their potential application in the modern-day over the others for the separation of a single cell from the mixture. In this review we also discuss the advantage of these methods and their modern–day applicability and acceptance in the forensic world.

Single cell genomics applications in forensic science: Current state and future directions

“…FACS enables separation of fluorescent antibody-labeled cells often relying on cell differences based on size, surface phenotype, cytoplasm, and DNA content. 47 FACS enables bulk cell enrichment typically separating two distinct cell population types. Reports have demonstrated FACS use in separating epithelial cells, 50 sperm, 51 blood, 52 and hormone specific cell fractions.…”

“…Magnetic activated cell sorting (MACS) can be utilized to separate cell populations based on cell specific antigens utilizing immune-magnetic beads usually coupled with antibodies. 47 MACS has been utilized to separate epithelial and sperm cell populations 54 , 55 as well as ABO blood groups. 56 In 2016, MACS was used in combination with FACS to separate individual sperm based on ABO blood groups.…”

“…However, for some case type scenarios, the mixed cell populations targeted for single cell capture and scDNA analysis can be first reduced in complexity from the bulk cell population via an enrichment process (e.g., DE) ( Figure 2 B). In this review we only briefly describe the enrichment methodology 47 for forensic genomics use as it pertains to be able to subsequently perform genetic analysis of single cells. Cell capture and subsequent scDNA analysis by STR-CE forms the main focus due to it being the principal genetic analysis method carried out to date, although other reported methodological applications such as mtDNA and MPS-based SNPs are discussed.…”