AP Biology class blog for discussing current research in Biology

Tag: Pig

Human Body Pig Kidney

For decades, scientists have been trying to figure out an alternative to conventional organ transplants due to the overwhelming need for human organs. With advancements in technology, a few experiments have been conducted with pig organs as an alternative, but mostly on brain-dead patients for safety. The exceptional pig-heart transplant on a living patient was unsuccessful, as the patient died shortly after the transplant. However, just recently, surgeons at Massachusetts General Hospital transplanted a pig kidney into a 62-year-old living patient, Richard Slayman. National Guard Kidney Transplant 099This surgery may be the first successful example of pig organ transplantation of many to come in the future, as he is expected to be discharged from the hospital soon. Slayman, who is recovering well after the kidney transplantation, sees his surgery not only as a way to help himself but also to provide hope for thousands of people in need of a transplant. Slayman has been on dialysis for the previous seven years after being diagnosed with type 2 diabetes and high blood pressure before a human kidney transplant in 2018, which showed signs of failure just five years later, restarting dialysis in 2023 and causing serious health problems. With the massive population in need of a human kidney, Slayman couldn’t have survived the wait time, according to his doctor Winfred Williams. The opportunity to receive a pig kidney became Slayman’s only hope as he later consented to the operation. Biotechnology company eGenesis uses the gene-editing system CRISPR to tweak the genes of pigs to make the pig organs suitable for people. With a total of 69 genetic edits in the pig’s DNA, the scientists took out sections of pig genes that the human immune system attacks and added seven human genes that help prevent immune-related problems possible of causing transplant rejection. In addition, they also disabled endogenous retroviruses in pigs’ genomes as they can hurt humans. This CRISPR technology has always been used in recent years to produce a solution to treat sickle cell disease, first approved in the U.K. and later in the U.S. in December 2023. CRISPR technologies have also been used to modify immune cells to attack tumors and cancerous cells in personalized cancer treatments. The apparent success of Slayman’s surgery represents not only a breakthrough in organ transplantation but also a potential solution to solving the unequal access for ethnic minorities to organ transplants and resources due to organ shortage and other problems. This connects to what we’ve learned in AP Biology on how different blood types can only receive blood donations of certain other blood types for their antigens exhibited. Carrying this to organ transplants means for some blood types, it’s extremely hard to find a matching organ for transplant. With this CRISPR pig kidney transplant marks a breakthrough in solving this problem. If you were to face an organ transplant, would you want to wait for years for a matching human organ or take the risk for a CRISPR pig organ?


CRISPR Gene Editing Provides Hope for Patients on Transplant List

Do you know anyone who has needed an organ transplant? Hopefully, the answer is no. However, many medical dramas on television have shown us the awful process patients go through when waiting on a transplant list for a heart, lung, kidney, etc.

For years, scientists have experienced many trials and errors. They explored pig parts and ways to supplement them as human organs. However, a huge advancement in gene editing has just reinstated hope for many suffering patients.  On March 16th, Richard Slayman received a pig kidney. He had type two diabetes and had been on dialysis. He had a transplant several years ago, but the organ showed signs of failure. Doctor Winfred Williams explained that Slay would not have survived if he had to wait another five years for a human kidney transplant.

National Guard Kidney Transplant 099

Eventually, the idea was proposed for Slayman to receive a genetically engineered pig kidney from eGenesis, a biotechnology company.  Their goal is to generate human-compatible organs that can be used in transplants. In Slayman’s case, this kidney had been genetically altered 69 times using the CRISPR-Cas9 gene editing system, which allows certain parts of a genome to be removed or even added. Slayman’s new kidney was made suitable for him in a very meticulous way. Firstly, three genes that are typically found in pigs that attack human immune systems were removed. These were genes that code for the synthesis of certain carbohydrates. Additionally, seven human genes were added to the genome that prevent an immune response that may lead to transplant rejection. Certain pig viruses were also removed as they pose a harm to humans.

This is very relevant to one of our last AP Biology units. We just learned about mRNA processing. This step occurs following mRNA transciption, with the goal of making certain proteins. After the nitrogenous bases are transcrribed from template DNA, the mRNA is processed in several ways. A Guanine cap is added to the front of the strand and a Poly-A tail is added to the end. Additionally, parts of the mRNA are cut out. In CRISPR editing, this same process is done by scientists artificially, rather than our natural processes. The parts of mRNA that are cut out that will not make a protein are called introns, while the kept parts of mRNA are called exons. mRNA splicing can also take place where different combinations of bases are organized to make certain amino acid chains.

4.5. The CRISPR Cas 9 system as a laboratory tool

This new advancement will not only help patients receive new organ quicker, but it is the doctors’ hope that this will solve a larger cultural issue, in that ethnic minorities often struggle to receive organ transplants. This new process will hopefully benefit the healthcare system both medically and culturally.

Cute Pigs Save the Day

Here, we might see two cute pigs having a lovely time, but biologist Luhan Yang sees otherwise; she sees life-saving organs!

With her remarkable Harvard background in genome-editing and bioengineering, Luhan Yang plans to use CRISPR to create pigs whose organs can be transplanted into people.

With miracles come challenges, which Luhan Yang faces a lot of! Luhan Yang is putting in front of herself the challenging of CRISPR’ing an unprecedented number of genes without being sure of the outcome. There is also the issue of money that needs to be raised.

Astonishingly, in 2015, Luhan Yang and her colleagues used CRISPR to eliminate 62 genes from pig cells that would have been dangerous they had been transplanted into humans. In March of 2017, Luhan Yang and her company, eGenesis, have raised $38 million from investors. These milestones have led Luhan Yang and her team to approach a new step where they get a surrogate mother that becomes pregnant with genetically altered embryos.

As successful as this idea sounds, Luhan Yang and her research team have stumbled upon many problems. One of them being the PERV genes that are interwoven into the genome of pig cells. In order to remove these genes though, the team uses CRISP-Cas9 to remove these genes. With these newly-edited cells, eGenesis ships many of these cells to China where each de-PERV’ed pig cell is fused with a pig ovum whose own DNA has been removed; this ova now contains solely the PERV-free genome. Unfortunately, all has not gone well as there have unfortunately been a lot of miscarriages and not all of the PERV-genes have been removed. Regardless of these setbacks, Luhan Yang is confident that she will make progress with her ideas and will push the limit of genomic technology.

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