Buffy Coats: Applications in Research, Diagnostics and Therapeutics

A buffy coat is the layer of white blood cells (WBCs) and platelets that forms following centrifugation of a blood sample.

When blood is collected in a vial and centrifuged at high speed, three distinct layers will form: 1) a bottom layer consisting of red blood cells, 2) an upper layer containing clear plasma and 3) a middle layer called the buffy coat.

The WBCs found in a buffy coat include granulocytes, monocytes, and lymphocytes. These cells play important roles in immunology and are used extensively to study disease.

Research Applications of Buffy Coats

The buffy coat is one of the most essential and valuable tools in immunology research.

Commercial blood banks are the primary suppliers of buffy coats and manufacture these products through standard centrifugation or use diminution filters to purify WBCs from whole blood.^[1]

Buffy coats are used in a diverse range of applications described below.

1. Cancer research: Buffy coats have promising applications in cancer research. They are a source of circulating tumor cells. Scientists at New York University recently published a study in which they used buffy coats to detect a type of lung cancer called malignant pleural mesothelioma. The analysis of the expressed mRNA of circulating immune cells present in the buffy coat (immuno-transcriptomics) is carried out. Thus, the buffy coat can be a possible resource for disease identification biomarkers.^[2] In addition to this, the buffy coat obtained from patients’ and healthy individuals’ blood is currently being used to predict certain miRNAs (non-coding RNA) that have a potential role in breast cancer pathogenesis. This approach will lead to the development of an effective, easy, and non-invasive detection method that may help in the early diagnosis of malignancies.^[3]
2. Regenerative medicine and tissue engineering applications: Bone marrow-derived buffy coats (BBCs) possess imperative osteogenic and chondrogenic precursor molecules that facilitate bone tissue formation. Thus, it can be a potential source in managing bone-related conditions such as avascular necrosis of the femoral head, a progressive ailment that leads to the deterioration of the hip joint. This condition can be promisingly treated via implantation of autologous (self) bone marrow buffy coat (BBC) in combination with the conventional surgical procedure, called core decompression.^[4] Buffy coats have also been studied for the potential of regenerating joint damage. Osteoarthritis leads to serious cartilage damage. There are limited treatment options to repair damaged cartilage. BBC has osteogenic and chondrogenic properties, thus can be used in cartilage tissue repair or engineering. Moreover, this can be an effective, feasible, and easily applicable method in treating osteoarthritis disease.^[5]
3. A rich platelet source: Platelets have many crucial medical applications. However, producing high-quality and sufficient yield of platelets is a significant concern. A buffy coat can be used to produce high-quality platelets in comparison to other production methods.^[6]
4. Epidemiological research: Frozen buffy coat samples can be used in epidemiological research studies or human biomonitoring investigations. A buffy coat sample can aid in analyzing the extent of DNA damage in response to any environmental changes.^[7]
5. Diagnosis of fungal infections: The buffy coat can be used to diagnose disseminated histoplasmosis in immune-compromised patients, an infection caused by the fungus histoplasma capsulatum. This buffy coat-based diagnostic method is quick and highly feasible for low-resource disease prevalent areas.^[8]
6. Diagnosis of parasitic infections: The buffy coat method is an emerging diagnostic approach for various blood parasites detection such as malaria and trypansomiasis. This is an optimized method that involves blood collection in heparinized capillaries, followed by centrifugation and direct microscopic examination of a buffy coat. It does not necessarily require lengthy staining procedures, thus proving a quick and easy method for fieldwork studies.^[9]
7. Improvement of platelet yields in cell culture: A buffy coat is an important source of CD34+ hematopoietic progenitor cells. They increase the yield of platelets from mature megakaryocytes, with improved functionality and molecular signaling in an in vitro system. In addition to being a direct source of platelets, buffy coats are a source of megakaryocytes for in vitro platelets production, overcoming the shortages of donor-derived platelets.^[10]
8. Genetic research: Due to their ease of collection and preparation, buffy coats can be used to extract genomic DNA for the study of various conditions.

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References

[1] Meyer T, Zehnter I, Hofmann B, Zaisserer J, Burkhart J, Rapp S, et al. Filter Buffy Coats (FBC): a source of peripheral blood leukocytes recovered from leukocyte depletion filters. Journal of immunological methods. 2005;307(1-2):150-66.

[2] Velez G, Pass H, Carbone M, Yang H, Goparaju C. Buffy Coat Immunotranscriptomics for Diagnosis of Malignant Pleural Mesothelioma. Cancer Research Journal. 2021;9(1):61.

[3] Donzelli S, Blandino G, Muti P. Use of buffy coat miRNA profiling for breast cancer prediction in healthy women.  Cancer Chemoprevention: Springer; 2016. p. 13-9.

[4] Ma Y, Wang T, Liao J, Gu H, Lin X, Jiang Q, et al. Efficacy of autologous bone marrow buffy coat grafting combined with core decompression in patients with avascular necrosis of femoral head: a prospective, double-blinded, randomized, controlled study. Stem Cell Research & Therapy. 2014;5(5):1-8.

[5] Li Z, Zhang Z, Song G, Fu S, Jin L, Liu Y. The Application Prospect Autologous Bone Marrow Extract Buffy Coat in Cartilage Tissue Engineering: A Mini-Review. Journal of Biosciences and Medicines. 2019;7(12):9-17.

[6] Levin E, Culibrk B, Gyöngyössy‐Issa MI, Weiss S, Scammell K, LeFresne W, et al. Implementation of buffy coat platelet component production: comparison to platelet‐rich plasma platelet production. Transfusion. 2008;48(11):2331-7.

[7] Bøhn SK, Vebraite V, Shaposhnikov S, Collins AR. Isolation of leukocytes from frozen buffy coat for comet assay analysis of DNA damage. Mutation Research/Genetic Toxicology and Environmental Mutagenesis. 2019;843:18-23.

[8] Leitão TM, Oliveira Filho AM, Sousa Filho JEP, Tavares BM, Mesquita JR, Farias LAB, et al. Accuracy of Buffy Coat in the Diagnosis of Disseminated Histoplasmosis in AIDS-Patients in an Endemic Area of Brazil. Journal of Fungi. 2019;5(2):47.

[9] Chagas CR, Binkienė R, Ilgūnas M, Iezhova T, Valkiūnas G. The buffy coat method: a tool for detection of blood parasites without staining procedures. Parasites & vectors. 2020;13(1):1-12.

[10] Marini I, Rigoni F, Zlamal J, Pelzl L, Althaus K, Nowak‐Harnau S, et al. Blood donor‐derived buffy coat to produce platelets in vitro. Vox sanguinis. 2020;115(1):94-102.