Knockout serum replacement as a substitute for exosome free serum

Document Type : Editorial

Author

1.Gametogenesis Research Center, Kashan University of Medical Sciences, Kashan, Iran.

Abstract

Exosomes, extracellular vesicles secreted from cells, are carriers containing proteins, lipids, and nucleic acids. By adhering and releasing their contents to the recipient cells, exosomes play a major role in cellular communication. Based on a variety of their originated cells, cargos, and physiologic state of releasing cell, Exosomes have been attributed an extended range of roles such as signal transduction, reprogramming, epigenetic modification, and inflammation. Recently, it has been shown that exosomes are also involved in pathological mechanisms of diseases, such as neurodegenerative diseases, tumours, chronic inflammation, and cardiovascular diseases. Moreover, exosomes have been used as diagnostic markers for different diseases since their cargos and contents can reflect physiological or pathological processes of the cells of origin. Because of having features of being carriers, they can be considered as a vehicle to drug delivery or gene therapy.

Highlights

  • Various protocols are currently used to isolate exosomes from cells cultured in vitro
  • Exosomes of the fetal bovine serum can be an interfering factor in cell exosome separation
  • Knockout serum replacement, exosome free serum, can be an alternative for cell culture and subsequently isolate exosome.

Keywords

Main Subjects

Full Text

Editorial: Exosomes, extracellular vesicles secreted from cells, are carriers containing proteins, lipids, and nucleic acids.By adhering and releasing their contents to the recipient cells, exosomes play a major role in cellular communication. Based on a variety of their originated cells, cargos, and physiologic state of releasing cell, Exosomes have been attributed an extended range of roles such as signal transduction, reprogramming, epigenetic modification, and inflammation (1). Recently, it has been shown that exosomes are also involved in pathological mechanisms of diseases, such as neurodegenerative diseases, tumours, chronic inflammation, and cardiovascular diseases (2). Moreover, exosomes have been used as diagnostic markers for different diseases since their cargos and contents can reflect physiological or pathological processes of the cells of origin. Because of having features of being the carrier, they can be considered as a vehicle to drug delivery or gene therapy (3). Due to the reasons above cited, researchers have been focused on isolation, characterization, and therapeutic application of exosomes from various cells using in vitro cell culture (4). Fetal bovine serum (FBS) because of having a lot of growth factors is widely used for in vitro cell culture but it also has high contentof exosomes which interfere with the characterization and isolation procedures of the cultivated cells. Thus, for eliminating exosomes of FBS, several protocols have been routinely applied using ultrafiltration, sonication, precipitation, and ultracentrifuge procedures which most of them are time-consuming and complex (5). In here, we suggest that knockout serum replacement (KSR) can be used instead of exosome-depleted FBS. KSR is a substitute for FBS in the culture of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) and also for when animal proteins might create an immunologic reaction in cases where the cells need to be injected for clinical application (6). 

 

Conclusions

KSR is an exosome-free serum since it has a defined formulation and stable concentration of ingredients. In summary, using an exosome-free serum is the first step for isolation and purification of exosomes from in vitro cell cultures and KSR can be a beneficial and efficient option than exosome-depleted FBS.

 

 

Authors’ contributions

Not applicable.

 

Acknowledgments

Special thanks to the Kashan University of Medical Sciences.

 

Conflict of interest

There is not any kind of conflict of interest.

 

Funding

There is no funding.

 

Ethical statement

Not applicable.

 

Data availability

Not applicable.

 

Abbreviations

ESCs       Embryonic stem cells

FBS         Fetal bovine serum 

iPSCs      Induced pluripotent stem cells

KSR        knockout serum replacement 

References

1. Zhang Y, Liu Y, Liu H, Tang WHJC, bioscience. Exosomes: biogenesis, biologic function and clinical potential. 2019;9(1):19.
2. Valadi H, Ekström K, Bossios A, Sjöstrand M, Lee JJ, Lötvall JOJNcb. Exosome-mediated transfer of mRNAs and microRNAs is a novel mechanism of genetic exchange between cells. 2007;9(6):654-9.
3. Greening DW, Gopal SK, Xu R, Simpson RJ, Chen W, editors. Exosomes and their roles in immune regulation and cancer. Seminars in cell & developmental biology; 2015: Elsevier.
4. Kishore R, Garikipati VNS, Gumpert AJJoctr. Tiny shuttles for information transfer: exosomes in cardiac health and disease. 2016;9(3):169-75.
5. Li P, Kaslan M, Lee SH, Yao J, Gao ZJT. Progress in exosome isolation techniques. 2017;7(3):789.
6. Zhang X, Wang L, Zhang X, Ren L, Shi W, Tian Y, et al. The use of KnockOut serum replacement (KSR) in three dimensional rat testicular cells co-culture model: An improved male reproductive toxicity testing system. 2017;106:487-95.

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History

  • Receive Date: 03 July 2020
  • Revise Date: 18 July 2020
  • Accept Date: 04 August 2020

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