Why does laser scatter and harm human embryos?

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The answer is refraction of different materials and Epicytohetics.

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Laser is the only effective tool for trophectoderm biopsy. Laser is a kind of electromagnetic radiation. The major laser systems used in Preimplantation Genetic Screening (PGS) are: “Saturn”, “OCTAX” and “LYKOS” or “ZILOS” systems with infrared “class 1” laser (1480 or 1460 nm wavelength). “Class 1” (according to international IEC 60825) is: “the light is contained in an enclosure, which will not directly radiate to our eyes”. However, the laser was mistakenly designed to point toward the human embryos. While facing laser, both our retinas and human embryos are vulnerable. The microtubules, actin, and other cell organelles in our human embryo cells and retina cells are harmed [Laband, et al., 2017;  Moore, et al., 2009]. The damage by laser in embryos is latent, which usually cannot be detected within 24 hours [Licciardi, et al., 1995; Uppangala, et al., 2016]. This kind of damage (such as the harm to microtubules) cannot be repaired, and will be inherited by future generations [Cui, 2019; Livshits, et al., 2017]. Many studies confirmed the safety of laser biopsy, and showed better results comparing with acid biopsy [Chatzimeletiou, et al., 2005; Veiga, et al., 1997; Geber, et al., 2011]. However, laser biopsy did cause visible and detrimental effects on embryonic and fetal development [Laband, et al. 2017;  Licciardi, et al., 1995].

 

In the air, laser light moves straight in long distance (refractive index: air: 1.00). However, during embryo biopsy, the laser light does not move straight. It first arrives at the mirror. It reflects and passes through the magnifying glass of the objective lens, the heating glass plate, the plastic dish, the medium and embryo zona. All of these objects contain different refractive index (water: 1.33; glass: 1.52; polystyrene dish: 1.6, etc.) and will produce high laser diffusion. After laser biopsy, people cannot directly observe any harm to the embryonic microtubules, or centrosome, or DNA under general microscope [Chatzimeletiou, et al., 2005] but the burnt and broken microtubules are obviously observed under electron tomography [Laband, et al. 2017]. Laser diffusion can be severe during biopsy. A simple example: The heating glass on the microscope is composed of tin dioxide which contains high refractive index. More than 20% laser light will be refracted by countless tiny tin dioxide “mirrors” to any direction, to all cells of the embryos and the manipulators’ eyes. In assisted hatching, fragmentation observed in the embryos was random and did not specifically originate from the blastomere adjacent to the site of laser [Uppangala, et al., 2016]. It showed that the laser is an invisible microtubule and centrosome cutting scattergun in embryo biopsy  [Laband, et al. 2017].

 

In insects and animals, lasers have shown very harmful effects. In a Drosophila experiment, embryos were radiated by laser and, while the doses did not eliminate nuclei or cells, up to 50% of adults from those embryos had defects in the thorax [Lohs-Schardin, et al., 1979]. In a zebrafish experiment, lasers produced centrosome disruption, which inhibited peripheral neural axon outgrowth. Some neurons had either no peripheral axon or short axons. Some of the cells also displayed ectopic protrusions of the axons from the nerve cell body [Andersen and Halloran 2012]. It confirmed that laser radiation can harm neuron differentiation, which can ultimately affect brain function. In mice, laser use was associated with increased DNA damage in embryos [Honguntikar, et al., 2015]. In other studies, many laser-exposed embryos exhibited morphologic aberrations such as isolated blastomere arrest and embryo growth delay; a significant decrease in fetal development [Licciardi, et al., 1995]; and significantly fewer cell numbers in completely hatched blastocysts compared to the control group [Honguntikar, et al., 2015; Chailert, et al., 2013]. When biopsy with laser, one group of mice pups were born with heavier hearts and another group with lighter kidneys. The laser radiation is harmful to the organ differentiation and pup health [Sepulveda-Rincon, et al., 2017].

 

In humans, embryo biopsy using laser also shows harmful effects: Laser-biopsied human embryos reached subsequent embryonic stages at significantly later time-points, which hindered the hatching [Kirkegaard, et al., 2012]. There was also a significantly lower mean number of nuclei in the laser-biopsied embryos on day 6 compared with the control group [Chatzimeletiou, et al., 2005]. Experiments performed in our laboratory and Vitrolife Company showed scary results: After blastocyst biopsy with laser cutting, freezing and thawing, sometimes all of the thawed blastocyst cells in some blastocysts were scattered singly on the culture dish without any cell to cell connection. This finding confirmed that laser harmed every cell (including the inner cell mass) in the blastocysts despite no observed signs of damage during biopsy or before freezing.

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Embryo biopsy with laser has produced Embryo Biopsy Syndrome in human babies. The reason was explained in the paper "Epicytohetics: preimplantation genetic testing for aneuploidy is not safe".

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References:

 

Andersen EF and Halloran MC. Centrosome movements in vivo correlate with specific neurite formation downstream of LIM homeodomain transcription factor activity. Develop. 2012;139:3590-9.

Chailert C, Sanmee U, Piromlertamorn W, Samchimchom S, Vutyavanich T. Effects of partial or complete laser-assisted hatching on the hatching of mouse blastocysts and their cell numbers. Reprod Biol Endocrin. 2013;11:21.

Chatzimeletiou, K, Morrison EE, Panagiotidis Y, Prapas N, Prapas Y, Rutherford AJ, et al. Comparison of effects of zona drilling by non-contact infrared laser or acid tyrode's on the development of human biopsied embryos as revealed by blastomere viability, cytoskeletal analysis and molecular cytogenetics. RBM Online. 2005;11:697-710.

Cui KH. Origin of life, heredity, differentiation and human reproduction: control of overpopulation and prohibition of subhuman reproduction. Letter to FDA, CDC and ASRM. March 15th, 2019.

Geber, S,  Bossi R,  Lisboa CB, Valle M, Sampaio M. Laser confers less embryo exposure than acid tyrode for embryo biopsy in preimplantation genetic diagnosis cycles: a randomized study. Reprod Biol Endocrinol. 2011;9:58.

Honguntikar SD, Uppangala S, Salian SR, Kalthur G, Kumar P, Adiga SK. Laser-assisted hatching of cleavage-stage embryos impairs developmental potential and increases DNA damage in blastocysts. Lasers Med Sci. 2015;30:95-101.

Kirkegaard K, Hindkjaer JJ, Ingerslev HJ. Human embryonic development after blastomere removal: a time-lapse analysis. Hum Reprod. 2012;27:97-105.

Laband K, Borgne RL, Edwards F, Stefanutti M, Canman JC, Verbavatz JM, et al. Chromosome segregation occurs by microtubule pushing in oocytes. Nature Commun. 2017;8:1499.

Licciardi F, Gonzalez A, Tang YX, Grifo J, Cohen J, Neev Y. Laser ablation of the mouse zona pellucida for blastomere biopsy. J Assist Reprod Genet. 1995;12:462-6.

Livshits A, Shani-Zerbib L, Maroudas-Sacks Y, Braun E, Keren K. Structural inheritance of the actin cytoskeletal organization determines the body axis in regenerating Hydra. Cell Rep. 2017;18:1410-21.

Lohs-Schardin M, Sander K, Cremer C, Cremer T, Zorn,C. Localized ultraviolet laser microbeam irradiation of early Drosophila embryos: fate maps based on location and frequency of adult defects. Devel Biol. 1979;68:533-45.

Moore JK, Magidson V, Khodjakov A, Cooper JA. The spindle position checkpoint requires positional feedback from cytoplasmic microtubules. Curr Biol. 2009;19:2026-30.

Sepulveda-Rincon LP, Islam N, Marsters P, Campbell BK, Beaujean N, Maalouf WE. Embryo cell allocation patterns are not altered by biopsy but can be linked with further development. Reprod. 2017;154:807-14.

Uppangala S, D’Souza F, Pudakalakatti S, Atreya HS, Raval K, Kalthur G, et al. Laser assisted zona hatching does not lead to immediate impairment in human embryo quality and metabolism. Sys Biol Reprod Med. 2016;62:396-403.

Veiga A, Sandalinas M, Benkhalifa M, Boada M, Carrera M, Santaló J, et al. Laser blastocyst biopsy for preimplantation diagnosis in the human. Zygote. 1997;5:351-4.

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