The Human Genome Project (HGP) helped determine the sequences of the three hundred million base pairs that make up human genome and identify all the approximately 50,000-100,000 genes in human DNA. Scientific research is making great strides. In the post-genomic era, robotized research and molecular diagnosis (MD) systems, such as the micro-array based comparative genomic hybridization (CGH), analyze thousands of genes in one single trial, detecting deletions or duplications of DNA segments of less than 1-2 Mb, in two DNA comparative samples, in hereditary disorders, malformations or cancer.

Molecular genetic engineering (MGE) alters the isolated DNA. Genetic therapy (GT) in somatic cells, used in human protocols, treats patients without effects on their descendents. GT in germinal cells prevents the outbreak of diseases by cutting the genetic chain and using ovules, spermatozoids or their precursors as substrates. It is used only in the creation of transgenic laboratory animals, food and drugs manufacturing, and biotechnology.

GT including stem cells is a tool to repair damaged tissues and heal diseases. Embryonic stem cells are pluripotent cells that give rise to the embryo. This helps form all the human tissues, treat diseases, decipher biological processes and assess new drugs. Adult stem cells come from the bone marrow, peripheral blood and umbilical cord. They are self-renewable and while they are not specialized, can produce cells from the same tissue of origin. The stem cells which are the precursors of hematopoietic cells can be used in bone marrow transplants in cases of hematological cancers. Stem cells can be obtained from alogenic transplantation of peripheral blood, with a cell production higher than the production at the bone marrow, and from the umbilical cord. When a child is born, stem cells can be separated, stored in tissue banks and let them grow and multiply as needed in the event of immunodeficiency or hematological-oncology diseases, or to repair any body failure.

In transplantations and total or partial replacement of organs, tissue repairing cells, once on the site, would proliferate and differentiate to repair the cell deficit.

Inserting in a plasmid the gene of the tissue regeneration would enable transportation up to the cell intended to be repaired. Transmiocardic percutaneous revascularization and infusion of growth factors, such as vascular endothelium and fibroblast growth factor, to promote angiogenesis, would help patients with diffuse coronary arterial diseases, resilient to conventional revascularization therapy, such as bypass or angioplasty.

Stem cell production is helpful in cell, collagen, dermis, cartilage regeneration therapies. Mesenchimatic adult stem cells from the bone marrow are a therapeutic potential in orthopedics and the musculoskeletical system, as they can be defined in mesodermic lines, such as bones, fatty tissue, cartilage, tendons and bone marrow stroma. Tests are being conducted on bioactive molecules as growth factor in growth medium to direct cell differentiation, replicate it and reimplant it in orthopedics.

Tissue differentiation, such as beta cells of insulin producing pancreatic islets could cure diabetes; heart muscle cells could repair an infarcted myocardium, or dopamine producing neurons could treat Parkinson's disease. Other cells in the nervous system could cure Alzheimer's disease or repair an injured spinal cord. The production of body "portions" and whole organs would be theoretically possible.

The cloning of Dolly the sheep through the nuclear transfer of the mammalian cell of an adult, six-year old sheep showed that a superior organism can be cloned from an adult cell. Therefore, theoretically, the legal impediment in many countries to research into fetuses that prevented cloning of a human was overcome.

Cloning of primates has been the closest to human cloning. However, the new nucleus obtained in apes is not in line with the ovule due to an abnormal cell division, lack of chromosome duplication and of an adequate separation of chromosomes during meiosis. Therefore, during the development stage of eight cells, some had a large amount of DNA and others lacked it at all. Human cloning needs a donor of a nucleus, a donor of the ovule, and a woman willing to make her uterus available. However, due to the experimental background in primates, human cloning will not be possible in the near future.

For most people, human cloning would violate fundamental human rights, such as equality and non-discrimination, and would be not appropriate in the area of determinism, the right not to be replicated, eugenesic temptation, and potential undesirable deviations towards biological sub-races or bio-slavery. However, positions in favor consider that it is too late not to move ahead. Legal implications, such as the paternity right, inheritance, blood-relation problems, identity disorders and freedom of procreation should be considered.

Genetic engineering and its applications are one of the most stunning challenges in modern technology. Molecular diagnosis, while beneficial, gives rise to ethical dilemmas, because the genetic information should remain confidential to prevent its use for discriminatory purposes. At the same time, direct intervention in the genetic load for preventive and therapeutic purposes is perhaps a longed-for accomplishment. However, it sets out deep religious, ethical, social justice, bio-political and bio-economic dilemmas. Every riddle emerges about the future of humankind, causing heated controversy and having a moral impact on the 21st Century society.

Aída Falcón de Vargas
Clinic Genetician, PhD in Human Genetics

Translated by Conchita Delgado

References
Bello, A. et al. (2002): La Transformación Genética de la Humanidad. ¿Jugar a Dios para Cosechar Poder? First Edition. Publicidad Gráfica León. Caracas

Kassirer, J.A. (1998): Human Cloning and the Challenge of Regulation. New England J. Med

Singer, M.; Berg, P.D.(1911) Genes and Genomes. A Changing Perspective. Blackwell Scientific Publications, Oxford.

Stracham,T.; Read, A.P.(1999). Genética Molecular Humana. Ediciones Omega, S.A.