Physics of the Future: How Science Will Shape Human Destiny and Our Daily Lives by the Year 2100 (23 page)

The third stage of medicine is molecular medicine. We are seeing the merger of physics and medicine, reducing medicine to atoms, molecules, and genes. This historic transformation began in the 1940s, when Austrian physicist Erwin Schrödinger, one of the founders of the quantum theory, wrote an influential book called
What Is Life?
He rejected the notion that there was some mysterious spirit, or life force, that animated living things. Instead, he speculated that all life was based on a code of some sort, and that this was encoded on a molecule. By finding that molecule, he conjectured, one could unravel the secret of life. Physicist Francis Crick, inspired by Schrödinger’s book, teamed up with geneticist James Watson to prove that DNA was this fabled molecule. In 1953, in one of the most important discoveries of all time, Watson and Crick unlocked the structure of DNA, a double helix. When unraveled, a single strand of DNA stretches about six feet long. On it is contained a sequence of 3 billion nucleic acids, called A,T,C,G (adenine, thymine, cytosine, and guanine), that carry the code. By reading the precise sequence of these nucleic acids placed along the DNA molecule, one could read the book of life.

The rapid advances in molecular genetics finally led to the creation of the Human Genome Project, truly a milestone in the history of medicine. A massive, crash program to sequence all the genes of the human body, it cost about $3 billion and involved the work of hundreds of scientists collaborating around the world. When it was finally completed in 2003, it heralded a new era in science. Eventually, everyone will have his or her personalized genome available on a CD-ROM. It will list all your approximately 25,000 genes; it will be your “owner’s manual.”

Nobel laureate David Baltimore summed it up when he said, “Biology is today an information science.”

What is driving this remarkable explosion in medicine is, in part, the quantum theory and the computer revolution. The quantum theory has given us amazingly detailed models of how the atoms are arranged in each protein and DNA molecule. Atom for atom, we know how to build the molecules of life from scratch. And gene sequencing—which used to be a long, tedious, and expensive process—is all automated with robots now. Originally, it cost several million dollars to sequence all the genes in a single human body. It is so expensive and time-consuming that only a handful of people (including the scientists who perfected this technology) have had their genomes read. But within a few more years, this exotic technology may come to the average person.

(I vividly recall keynoting a conference in the late 1990s in Frankfurt, Germany, about the future of medicine. I predicted that by 2020, personal genomes would be a real possibility, and that everyone might have a CD or chip with his or her genes described on it. But one participant became quite indignant. He rose and said that this dream was impossible. There were simply too many genes, and it would cost too much to offer personal genomes to the average person. The Human Genome Project had cost $3 billion; the cost to sequence one person’s genes could not possibly drop that much. Discussing the issue with him later, it gradually became clear what the problem was. He was thinking linearly. But Moore’s law was driving down the costs, making it possible to sequence DNA using robots, computers, and automatic machines. He failed to understand the profound impact of Moore’s law on biology. Looking back at that incident, I now realize that if there was a mistake in that prediction, it was in overestimating the time it would take to offer personal genomics.)

For example, Stanford engineer Stephen R. Quake has perfected the latest development in gene sequencing. He has now driven down the cost to $50,000 and foresees the price plunging to $1,000 in the next few years. Scientists have long speculated that when the price of human gene sequencing drops to $1,000, this could open the floodgates to mass gene sequencing, so a large proportion of the human race may benefit from this technology. Within a few decades, the price of sequencing all your genes may cost less than $100, no more expensive than a standard blood test.

(The key to this latest breakthrough is to take a shortcut. Quake compares a person’s DNA to DNA sequences that have already been done of others. He breaks up the human genome into units of DNA containing 32 bits of information. Then he has a computer program that compares these 32-bit fragments to the completed genomes of other people. Since any two humans are almost identical in their DNA, differing on average by less than .1 percent, this means that a computer can rapidly get a match among these 32-bit fragments.)

Quake became the eighth person in the world to have his genome fully sequenced. He had a personal interest in this project as well, since he scanned his personal genome for evidence of heart disease. Unfortunately, his genome indicated that he inherited one version of a gene associated with heart disease. “You have to have a strong stomach when you look at your own genome,” he lamented.

I know that eerie feeling. I had my own genome partially scanned and placed on a CD-ROM for a BBC-TV/Discovery special that I hosted. A doctor extracted some blood from my arm; sent it to the laboratory at Vanderbilt University; and then, two weeks later, a CD-ROM came back in the mail, listing thousands of my genes. Holding this disk in my hands gave me a funny feeling, knowing that it contained a partial blueprint for my body. In principle, this disk could be used to create a reasonable copy of myself.

But it also piqued my curiosity, since the secrets of my body were contained on that CD-ROM. For example, I could see if I had a particular gene that increased my chances of getting Alzheimer’s disease. I was concerned, since my mother died of Alzheimer’s. (Fortunately, I do not have the gene.)

Also, four of my genes were matched with the genome of thousands of people around the world, who had also had their genes analyzed. Then, the locations of the individuals who had a perfect match with my four genes were placed on a map of the earth. By analyzing the dots on the map of the earth, I could see a long trail of dots, originating near Tibet and then stretching through China and to Japan. It was amazing that this trail of dots traced the ancient migration patterns of my mother’s ancestors, going back thousands of years. My ancestors left no written records of their ancient migration, but the telltale map of their travels was etched into my blood and DNA. (You can also trace the ancestry of your father. The mitochondrial genes are passed down unchanged from mother to daughter, while the Y chromosome is passed down from father to son. Hence, by analyzing these genes, one can trace the ancestry of your mother or your father’s line.)

I imagine in the near future, many people will have the same strange feeling I did, holding the blueprint of their bodies in their hands and reading the intimate secrets, including dangerous diseases, lurking in the genome and the ancient migration patterns of their ancestors.

But for scientists, this is opening an entirely new branch of science, called bioinformatics, or using computers to rapidly scan and analyze the genome of thousands of organisms. For example, by inserting the genomes of several hundred individuals suffering from a certain disease into a computer, one might be able to calculate the precise location of the damaged DNA. In fact, some of the world’s most powerful computers are involved in bioinformatics, analyzing millions of genes found in plants and animals for certain key genes.

This could even revolutionize TV detective shows like
CSI.
Given tiny scraps of DNA (found in hair follicles, saliva, or bloodstains), one might be able to determine not just the person’s hair color, eye color, ethnicity, height, and medical history, but perhaps also his face. Today, police artists can mold an approximate sculpture of a victim’s face using only the skull. In the future, a computer might be able to reconstruct a person’s facial features given just some dandruff or blood from that person. (The fact that identical twins have remarkably similar faces means that genetics alone, even in the presence of environmental factors, can determine much of a person’s face.)

As we mentioned in the previous chapters, your visit to the doctor’s office will be radically changed. When you talk to the doctor in your wall screen, you will probably be talking to a software program. Your bathroom will have more sensors than a modern hospital, silently detecting cancer cells years before a tumor forms. For example, about 50 percent of all common cancers involve a mutation in the gene p53 that can be easily detected using these sensors.

If there is evidence of cancer, then nanoparticles will be injected directly into your bloodstream, which will, like smart bombs, deliver cancer-fighting drugs directly to the cancer cells. We will view chemotherapy today like we view leeches of the past century. (We will discuss the details of nanotechnology, DNA chips, nanoparticles, and nanobots in more detail in the next chapter.)

And if the “doctor” in your wall screen cannot cure a disease or injury to an organ, you will simply grow another. In the United States alone, there are 91,000 people awaiting an organ transplant. Eighteen die every day, waiting for an organ that never comes.

In the future, we will have tricorders—like these in
Star Trek
—that can diagnose almost any disease; portable MRI detectors and DNA chips will make this possible. (
photo credit 3.1
)

If your virtual doctor finds something wrong, such as a diseased organ, then he might order a new one to be grown directly from your own cells. “Tissue engineering” is one of the hottest fields in medicine, making possible a “human body shop.” So far, scientists can grow skin, blood, blood vessels, heart valves, cartilage, bone, noses, and ears in the lab from your own cells. The first major organ, the bladder, was grown in 2007, the first windpipe in 2009. So far, the only organs that have been grown are relatively simple, involving only a few types of tissues and few structures. Within five years, the first liver and pancreas might be grown, with enormous implications for public health. Nobel laureate Walter Gilbert told me that he foresees a time, just a few decades into the future, when practically every organ of the body will be grown from your own cells.

Tissue engineering grows new organs by first extracting a few cells from your body. These cells are then injected into a plastic mold that looks like a sponge shaped in the form of the organ in question. The plastic mold is made of biodegradable polyglycolic acid. The cells are treated with certain growth factors to stimulate cell growth, causing them to grow into the mold. Eventually, the mold disintegrates, leaving behind a perfect organ.

I had the opportunity to visit Anthony Atala’s laboratory at Wake Forest University in North Carolina and witness this miraculous technology firsthand. As I walked through his laboratory, I saw bottles that contained living human organs. I could see blood vessels and bladders; I saw heart valves that were constantly opening and closing because liquids were being pumped through them. Seeing all these living human organs in bottles, I almost felt as if I were walking through Dr. Frankenstein’s laboratory, but there were several crucial differences. Back in the nineteenth century, doctors were ignorant of the body’s rejection mechanism, which makes it impossible to graft new organs. Plus, doctors did not know how to stop the infections that would inevitably contaminate any organ after surgery. So Atala, instead of creating a monster, is opening an entirely new lifesaving medical technology that may one day change the face of medicine.

One future target for his laboratory is to grow a human liver, perhaps within five years. The liver is not that complicated and consists of only a few types of tissue. Lab-grown livers could save thousands of lives, especially those in desperate need of liver transplants. It could also save the lives of alcoholics suffering from cirrhosis. (Unfortunately, it could also encourage people to keep bad habits, knowing that they can get replacement organs for their damaged ones.)

If organs of the body, like the windpipe and the bladder, can be grown now, what is to prevent scientists from growing every organ of the body? One basic problem is how to grow the tiny capillaries that provide blood for the cells. Every cell in the body has to be in contact with a blood supply. In addition, there is the problem of growing complex structures. The kidney, which purifies the blood of toxins, is composed of millions of tiny filters, so a mold for these filters is quite difficult to create.