- Email: [email protected]
Limitations on the cloning of humans and other mammals
Medical Hypotheses (2004) 63, 254–256
http://intl.elsevierhealth.com/journals/mehy
Limitations on the cloning of humans and other mammals D.S. Robertson 205 Pickersleigh Road, Malvern, Worcestershire WR14 2QS, UK Received 11 December 2003; accepted 2 February 2004
Summary The nature of clones is discussed along with the origin and principles of the concept that human and other mammalian clones can be produced. The physical and chemical properties of living cells are described and it is shown these properties place severe limitations on attempts to bring human and mammalian clones into being. The observed result of such attempts that a large number of distorted and aborted foetii have been produced is demonstrated to have been predictable. Offspring produced by such attempts cannot be classified under any of the normal classifications of human relationships e.g. son, daughter, brother, sister or twin and that such offspring are entirely unnatural and likely to be metabollically unstable. It is concluded that the cloning of humans and other mammals is difficult, certainly dangerous and perhaps impossible. c 2004 Elsevier Ltd. All rights reserved.
In animal reproduction a clone is defined as the offspring of an organism which reproduces asexually. It is theoretically possible to transfer a body cell nucleus from a mature human female to one of her own ovum from which the nucleus has been removed, the activation of the altered ovum without the use of sperm from a human male, the implantation of the activated ovum in her own womb and for the result to be an offspring. In true cloning the natural mother generates the DNA, both in base order and amount, in her ova and all other dividing cells. This means that this mother can clearly supply the chemicals necessary at the required rate and in the required concentration to a foetus derived from her own ova. The fetus is metabolically compatible and would not suffer rejection as foreign tissue or kill the mother as the result of its
E-mail address: [email protected].
waste products being metabolically incompatible with the maternal metabolism. Under these circumstances the female involved can be said to have reproduced herself and the offspring is correctly described as a clone. This operation would be expected invariably to give rise to female offspring and on this basis cloning human males is impossible. Production of an offspring is also possible by taking the nucleus of any cell from any human, inserting this nucleus into an ovum of the mother of this human, from which the ovum nucleus has been removed, activating the altered ovum without the use of sperm from the father of the human and inserting the activated ovum into the womb of the mother of the human. The offspring will not be a clone but a non identical twin of the human whose cell nucleus was used. Attempts to clone humans and other mammals do not follow this procedure. It should be noted that the procedure cannot give rise to an identical twin since the full mitochondrial
0306-9877/$ - see front matter c 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.mehy.2004.02.016
Limitations on the cloning of humans and other mammals compliment of the ovum is used in the procedure. In identical twins this compliment is divided between the two ova formed by separation of a single ovum. The origin of all present cloning experiments are papers published some fifty years ago [1]. The first work succeeded in obtaining tadpoles by a procedure involving the transfer of the nucleus of a fertilised amphibian ovum to another fertilised ovum from which the nucleus had been removed giving rise to an adult frog. As the age of the dividing ovum measured from the time of fertilisation increased the transferred nuclei of such an ovum only gave rise to tadpoles which did not develop further. The transfer of the nucleus of a cell from the amphibian digestive system into a fertilised amphibian ovum from which the nucleus had been removed again only developed to the tadpole stage of the amphibian life cycle [2]. In each case the tadpoles were described as clones. This is only true when nuclei from the amphibian cells were transferred into ova produced by the same amphibian. The work lead to the concept that embryonic cells are capable of developing into any of the many cells in the amphibian metabolism (totipotent) while cells from any part of the adult amphibian are not so capable on the grounds that these cells had changed (differentiated) to have a single function only. The use of differentiated cells in attempts to repeat the above procedure with mammals encountered similar difficulties. A reason advanced for this situation was that the nature of the differentiated cell, non dividing (muscle and nerve cells) or rapidly dividing (skin and digestive system epithelial cells) was important. For the procedure described above it was concluded that rapidly dividing cells were preferred. It was further concluded that if this type cell was to be used then this had to be placed in a temporary non dividing state during the transfer. Using this procedure and the activation of the converted ovum with an electric pulse is the procedure recorded as giving rise to an animal described as a mammalian clone [3,4]. An arrangement of DNA in a cell which is agreement with observation and experiment has been described [5]. DNA is arranged in a cell nucleus somewhat in the form of the segments of an orange. The number of segments and the amount of DNA in each segment are the factors which decide the form of an animal. The slightest change in either of these factors alters the physical characteristics of the animal. Such a change happens naturally in humans and gives rise to offspring with Down’s Syndrome. A precise compliment of DNA is required in any cell nucleus to induce division of the cell [5]. Cell division is an internal charge effect. The function of a sperm in reproduction is to complete the compli-
255
ment of DNA in the ovum leading to division [5]. DNA controls cell division and hence the number of a particular cell in a metabolism. In turn the number of particular cells controls the amount of the cell product (tissue, protein, etc.) produced in the metabolism. The separation of an ovum into two sections giving rise to identical twins in mammals arises from the simultaneous entry of several sperm into the single ovum on the basis of arrangement of DNA in the cell nucleus. The construction of the nucleus means that it is extremely difficult to extract a nucleus from any cell and transfer this nucleus to another cell, devoid of a nucleus, without causing damage or a change in the segments of DNA in the transferred nucleus. The compliment of DNA in any non dividing adult body cell, irrespective of type, is close to the compliment required to cause division. Division will only occur when a further supply of the base and sugar molecules or the components required to form these molecules which are linked to give DNA molecules reaches the cell nucleus [6]. The continued division of a dividing adult body cell when transferred into a fertilised ovum indicates that there is a supply of the compounds from which DNA is formed within the ovum. This supply is sufficient to allow development of the amphibian embryo to the foetal stage. Thereafter the supply of the component molecules is from the diet of the free swimming tadpole. The division of any cell, including ova, is also related to the pH of the nucleus cytoplasm which is controlled by enzymes [5]. The sperm supplies enzymes to the developing ovum which will be absent in ova activated without sperm action. The pH and changes in the pH of the nucleus and main cell cytoplasm in such an ovum will deviate from those in sperm activated ova. In an adult body cell the product of the cell (tissue protein, enzymes, carbohydrate, etc.) is decided principally by the nature and concentration of chemicals reaching the cell and the enzymes present in the cell. In a foetus the differentiation of cells begins when fluid movement in the ovum cytoplasm commences resulting from cell division. This movement induces a non uniform distribution of chemical compounds within the ovum. The transfer of an adult cell nucleus to a fertilised ovum, devoid of a nucleus, will inevitably result in the transfer of some of the other cytoplasm components particularly enzymes. The latter will interfere with the normal ovum products leading to faults in the developing embryo and foetus. The result is that normal development is inhibited. A procedure of ‘fusing’ is described as being used by the programmes which attempt to generate mammalian offspring using the nucleus
256 transfer procedure outlined above. The process involves the application of electric current to the ovum plus transferred cell nucleus. This action is described as amalgamating the transferred nucleus into the ovum cytoplasm. The cytoplasm of cells is a hydrophillic sol. One of the properties of a hydrophillic sol is that the presence of small amounts of charged particles, derived from ionised electrolytes in the hydrophillic sol, have little effect [7]. However large amounts cause the colloidal particles of the sol to form gelatinous solid precipitates as a result of annulment of the charge between the particles forming the sol. Reduction of the ion concentration results in the gelatinous solid precipitates redissolving. The electric current or electric discharge used in the above procedure will cause precipitation of gelatinous solids in the cytoplasm of the ovum into which nucleus transfer has taken place. These solids will not dissolve until the charge disperses. This may happen slowly, quickly or never at all. Cell division being a charge effect [5] the applied current is likely to artificially initiate division of the transferred nucleus under conditions where there insufficient DNA or the components of this molecule to continue division. The applied electric current is also likely to disrupt the DNA structure of the ovum mitochondria. The nuclei of male cells contain slightly less DNA giving rise to one less complete plane than female nuclei [5]. This means that charge activation leading to division of an ovum containing a transferred male nucleus will be less effective. In the above procedure the division of the ovum is in vitro and there is no means to supply the chemical components required to form DNA from outside the altered ovum. A ‘fused’ ovum which continues to divide must therefore use the DNA from the mitochondria present in the ovum. When this supply fails division will cease. Such an ovum is now defective on four counts, it contains or can contain inappropriate solids, inappropriate enzymes from the cell from which the transfer was made, no sperm enzymes functioning as described, and is deficient in mitochondria. In mammals the ovum develops internally and ova transplanted into a surrogate womb means that nuclei are metabolically incompatible in the sense that the surrogate maternal metabolism is not ‘tuned’ to supply the chemicals necessary to continue the duplication of the ‘foreign’ DNA in embryo/foetus. Where the maternal
Robertson metabolism, either natural or surrogate, cannot supply the chemicals necessary, in the correct concentration and at the correct rate, to continue the duplication of DNA in the already defective embryo/foetus cells then cell division will cease and the embryo/foetus will be rejected (aborted). Taking account of all of the circumstances given above a high failure rate of ova with transplanted nuclei is to be expected and is found. Procedures using the above techniques are therefore dangerous and damage to the nucleus is likely to be the main reason for the very large number of aborted and misshapen embryos that have been encountered in attempts to clone mammals. On the basis of the definition of a clone given above and the procedure used to give rise to mammalian offspring [3,4] means that these offspring were not clones and on the basis of the procedure used were not even non identical twins. The procedure used can never occur naturally and therefore the animal can only be described as an unstable metabolic forgery. The early death of the animal clearly indicates that all such artificial duplicates are likely to be unstable including any human versions. It is concluded that attempts to produce artificial mammalian offspring by the methods described above are not without danger and the practical difficulties outlined may never be overcome.
References [1] Briggs R, King TJ. Transplantation of living nuclei from blastula cells into enucleated frogs eggs. Proc Nat Acad Sci USA 1952;38:455–63. [2] Gurdon JB. The developmental capacity of nuclei taken from intestinal epithelium cells of feeding tadpoles. J Embryol Exp Morph 1962;10:622–40. [3] Wilmut I, Schnieke AE, McWhir J, Kind AJ, Campbell KH. Viable offspring derived from fetal and adult mammalian cells. Nature 1997;385:810–3. [4] Campbell KHS. Cloning Dolly: implications for human medicine. In: Kempers RD, Cohen J, Haney AF, Younger JB, editors. Fertility and reproductive medicine. (Excerpta Medica: International Congress series 1183); 1998. p. 3–11. [5] Robertson DS. Cellular configuration of DNA and cell division. Med Hypothesis 2001;57(3):344–53. [6] Robertson DS. Cellular formation of DNA and RNA and the relationship to tumour cell development. Med Hypoth 2004;62:97–111. [7] Glasstone S. Textbook of physical chemistry. London: MacMillan and Co Ltd; 1955.
http://intl.elsevierhealth.com/journals/mehy
Limitations on the cloning of humans and other mammals D.S. Robertson 205 Pickersleigh Road, Malvern, Worcestershire WR14 2QS, UK Received 11 December 2003; accepted 2 February 2004
Summary The nature of clones is discussed along with the origin and principles of the concept that human and other mammalian clones can be produced. The physical and chemical properties of living cells are described and it is shown these properties place severe limitations on attempts to bring human and mammalian clones into being. The observed result of such attempts that a large number of distorted and aborted foetii have been produced is demonstrated to have been predictable. Offspring produced by such attempts cannot be classified under any of the normal classifications of human relationships e.g. son, daughter, brother, sister or twin and that such offspring are entirely unnatural and likely to be metabollically unstable. It is concluded that the cloning of humans and other mammals is difficult, certainly dangerous and perhaps impossible. c 2004 Elsevier Ltd. All rights reserved.
In animal reproduction a clone is defined as the offspring of an organism which reproduces asexually. It is theoretically possible to transfer a body cell nucleus from a mature human female to one of her own ovum from which the nucleus has been removed, the activation of the altered ovum without the use of sperm from a human male, the implantation of the activated ovum in her own womb and for the result to be an offspring. In true cloning the natural mother generates the DNA, both in base order and amount, in her ova and all other dividing cells. This means that this mother can clearly supply the chemicals necessary at the required rate and in the required concentration to a foetus derived from her own ova. The fetus is metabolically compatible and would not suffer rejection as foreign tissue or kill the mother as the result of its
E-mail address: [email protected].
waste products being metabolically incompatible with the maternal metabolism. Under these circumstances the female involved can be said to have reproduced herself and the offspring is correctly described as a clone. This operation would be expected invariably to give rise to female offspring and on this basis cloning human males is impossible. Production of an offspring is also possible by taking the nucleus of any cell from any human, inserting this nucleus into an ovum of the mother of this human, from which the ovum nucleus has been removed, activating the altered ovum without the use of sperm from the father of the human and inserting the activated ovum into the womb of the mother of the human. The offspring will not be a clone but a non identical twin of the human whose cell nucleus was used. Attempts to clone humans and other mammals do not follow this procedure. It should be noted that the procedure cannot give rise to an identical twin since the full mitochondrial
0306-9877/$ - see front matter c 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.mehy.2004.02.016
Limitations on the cloning of humans and other mammals compliment of the ovum is used in the procedure. In identical twins this compliment is divided between the two ova formed by separation of a single ovum. The origin of all present cloning experiments are papers published some fifty years ago [1]. The first work succeeded in obtaining tadpoles by a procedure involving the transfer of the nucleus of a fertilised amphibian ovum to another fertilised ovum from which the nucleus had been removed giving rise to an adult frog. As the age of the dividing ovum measured from the time of fertilisation increased the transferred nuclei of such an ovum only gave rise to tadpoles which did not develop further. The transfer of the nucleus of a cell from the amphibian digestive system into a fertilised amphibian ovum from which the nucleus had been removed again only developed to the tadpole stage of the amphibian life cycle [2]. In each case the tadpoles were described as clones. This is only true when nuclei from the amphibian cells were transferred into ova produced by the same amphibian. The work lead to the concept that embryonic cells are capable of developing into any of the many cells in the amphibian metabolism (totipotent) while cells from any part of the adult amphibian are not so capable on the grounds that these cells had changed (differentiated) to have a single function only. The use of differentiated cells in attempts to repeat the above procedure with mammals encountered similar difficulties. A reason advanced for this situation was that the nature of the differentiated cell, non dividing (muscle and nerve cells) or rapidly dividing (skin and digestive system epithelial cells) was important. For the procedure described above it was concluded that rapidly dividing cells were preferred. It was further concluded that if this type cell was to be used then this had to be placed in a temporary non dividing state during the transfer. Using this procedure and the activation of the converted ovum with an electric pulse is the procedure recorded as giving rise to an animal described as a mammalian clone [3,4]. An arrangement of DNA in a cell which is agreement with observation and experiment has been described [5]. DNA is arranged in a cell nucleus somewhat in the form of the segments of an orange. The number of segments and the amount of DNA in each segment are the factors which decide the form of an animal. The slightest change in either of these factors alters the physical characteristics of the animal. Such a change happens naturally in humans and gives rise to offspring with Down’s Syndrome. A precise compliment of DNA is required in any cell nucleus to induce division of the cell [5]. Cell division is an internal charge effect. The function of a sperm in reproduction is to complete the compli-
255
ment of DNA in the ovum leading to division [5]. DNA controls cell division and hence the number of a particular cell in a metabolism. In turn the number of particular cells controls the amount of the cell product (tissue, protein, etc.) produced in the metabolism. The separation of an ovum into two sections giving rise to identical twins in mammals arises from the simultaneous entry of several sperm into the single ovum on the basis of arrangement of DNA in the cell nucleus. The construction of the nucleus means that it is extremely difficult to extract a nucleus from any cell and transfer this nucleus to another cell, devoid of a nucleus, without causing damage or a change in the segments of DNA in the transferred nucleus. The compliment of DNA in any non dividing adult body cell, irrespective of type, is close to the compliment required to cause division. Division will only occur when a further supply of the base and sugar molecules or the components required to form these molecules which are linked to give DNA molecules reaches the cell nucleus [6]. The continued division of a dividing adult body cell when transferred into a fertilised ovum indicates that there is a supply of the compounds from which DNA is formed within the ovum. This supply is sufficient to allow development of the amphibian embryo to the foetal stage. Thereafter the supply of the component molecules is from the diet of the free swimming tadpole. The division of any cell, including ova, is also related to the pH of the nucleus cytoplasm which is controlled by enzymes [5]. The sperm supplies enzymes to the developing ovum which will be absent in ova activated without sperm action. The pH and changes in the pH of the nucleus and main cell cytoplasm in such an ovum will deviate from those in sperm activated ova. In an adult body cell the product of the cell (tissue protein, enzymes, carbohydrate, etc.) is decided principally by the nature and concentration of chemicals reaching the cell and the enzymes present in the cell. In a foetus the differentiation of cells begins when fluid movement in the ovum cytoplasm commences resulting from cell division. This movement induces a non uniform distribution of chemical compounds within the ovum. The transfer of an adult cell nucleus to a fertilised ovum, devoid of a nucleus, will inevitably result in the transfer of some of the other cytoplasm components particularly enzymes. The latter will interfere with the normal ovum products leading to faults in the developing embryo and foetus. The result is that normal development is inhibited. A procedure of ‘fusing’ is described as being used by the programmes which attempt to generate mammalian offspring using the nucleus
256 transfer procedure outlined above. The process involves the application of electric current to the ovum plus transferred cell nucleus. This action is described as amalgamating the transferred nucleus into the ovum cytoplasm. The cytoplasm of cells is a hydrophillic sol. One of the properties of a hydrophillic sol is that the presence of small amounts of charged particles, derived from ionised electrolytes in the hydrophillic sol, have little effect [7]. However large amounts cause the colloidal particles of the sol to form gelatinous solid precipitates as a result of annulment of the charge between the particles forming the sol. Reduction of the ion concentration results in the gelatinous solid precipitates redissolving. The electric current or electric discharge used in the above procedure will cause precipitation of gelatinous solids in the cytoplasm of the ovum into which nucleus transfer has taken place. These solids will not dissolve until the charge disperses. This may happen slowly, quickly or never at all. Cell division being a charge effect [5] the applied current is likely to artificially initiate division of the transferred nucleus under conditions where there insufficient DNA or the components of this molecule to continue division. The applied electric current is also likely to disrupt the DNA structure of the ovum mitochondria. The nuclei of male cells contain slightly less DNA giving rise to one less complete plane than female nuclei [5]. This means that charge activation leading to division of an ovum containing a transferred male nucleus will be less effective. In the above procedure the division of the ovum is in vitro and there is no means to supply the chemical components required to form DNA from outside the altered ovum. A ‘fused’ ovum which continues to divide must therefore use the DNA from the mitochondria present in the ovum. When this supply fails division will cease. Such an ovum is now defective on four counts, it contains or can contain inappropriate solids, inappropriate enzymes from the cell from which the transfer was made, no sperm enzymes functioning as described, and is deficient in mitochondria. In mammals the ovum develops internally and ova transplanted into a surrogate womb means that nuclei are metabolically incompatible in the sense that the surrogate maternal metabolism is not ‘tuned’ to supply the chemicals necessary to continue the duplication of the ‘foreign’ DNA in embryo/foetus. Where the maternal
Robertson metabolism, either natural or surrogate, cannot supply the chemicals necessary, in the correct concentration and at the correct rate, to continue the duplication of DNA in the already defective embryo/foetus cells then cell division will cease and the embryo/foetus will be rejected (aborted). Taking account of all of the circumstances given above a high failure rate of ova with transplanted nuclei is to be expected and is found. Procedures using the above techniques are therefore dangerous and damage to the nucleus is likely to be the main reason for the very large number of aborted and misshapen embryos that have been encountered in attempts to clone mammals. On the basis of the definition of a clone given above and the procedure used to give rise to mammalian offspring [3,4] means that these offspring were not clones and on the basis of the procedure used were not even non identical twins. The procedure used can never occur naturally and therefore the animal can only be described as an unstable metabolic forgery. The early death of the animal clearly indicates that all such artificial duplicates are likely to be unstable including any human versions. It is concluded that attempts to produce artificial mammalian offspring by the methods described above are not without danger and the practical difficulties outlined may never be overcome.
References [1] Briggs R, King TJ. Transplantation of living nuclei from blastula cells into enucleated frogs eggs. Proc Nat Acad Sci USA 1952;38:455–63. [2] Gurdon JB. The developmental capacity of nuclei taken from intestinal epithelium cells of feeding tadpoles. J Embryol Exp Morph 1962;10:622–40. [3] Wilmut I, Schnieke AE, McWhir J, Kind AJ, Campbell KH. Viable offspring derived from fetal and adult mammalian cells. Nature 1997;385:810–3. [4] Campbell KHS. Cloning Dolly: implications for human medicine. In: Kempers RD, Cohen J, Haney AF, Younger JB, editors. Fertility and reproductive medicine. (Excerpta Medica: International Congress series 1183); 1998. p. 3–11. [5] Robertson DS. Cellular configuration of DNA and cell division. Med Hypothesis 2001;57(3):344–53. [6] Robertson DS. Cellular formation of DNA and RNA and the relationship to tumour cell development. Med Hypoth 2004;62:97–111. [7] Glasstone S. Textbook of physical chemistry. London: MacMillan and Co Ltd; 1955.