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Long-term survival of monkey with transplanted pig kidney offers hope in alternative organ search: Scientists_我的网站

A |     Harvard-affiliated scientists say they have been able to keep a monkey alive for two years with a genetically engineered pig kidney. Although preliminary, transplant experts say this research is an important milestone in the search for an alternative source of organs.Scientists are hopeful that one day, genetically modified organs grown in pigs may be able to significantly extend the life of people with end-stage organ failure.In recent months, other high-profile research teams at New York University and the University of Alabama at Birmingham announced successful transplants of genetically modified pig-kidneys into brain dead human donors. But those experiments ended after a few weeks."Duration of survival has been an Achilles heel of genetically modified pig organs to date due to a combination of rejection and opportunistic infections," said Dr. Peter Chin-Hong, director of the transplant infectious disease program at University of California, San Francisco.This new research, published in Nature, represents the longest period of time that scientists have been able to keep a non-human primate research animal alive."This proof-of-concept study provides real hope that transplantation of porcine [pig] donor kidneys into humans is very much on the horizon," Chin-Hong said.Still, experts cautioned that this new research was preliminary, and the idea of pig-grown organs is likely several years away from becoming a reality."If ultimately proved successful in human organ recipients - which is still years away at this point - this could be one of the key advances needed to make xenotransplantation a reality in clinical practice," said Dr. Josh Levitsky, president of the American Society of Transplantation.The new research was led by eGenesis, a company co-founded by Harvard geneticist George Church. In a press release, scientists at eGenesis said the new research will help lay the groundwork for formal clinical trials.In prepared remarks, eGenesis CEO Michael Curtis, PhD, said the company is focused on "improving long-term survival for transplant recipients from months to years."Eventually, the hope is that transplant doctors will be able to use genetically modified pig organs instead of solely relying on deceased human organ donors."Among all solid organs transplanted, kidneys are most sought after, expected to increase in demand further, and there is a significant shortfall of organs leading to premature deaths," Chin-Hong said.Every day, 17 people die waiting on the organ transplant list, according to the Health Resources & Services Administration. There are currently more than 100,000 people waiting on the national transplant list and a new person is added to the list every 10 minutes.。    

    Illustration: Xia Qing/GT
The yen has weakened in recent days, edging closer to the psychologically important 160 level against the US dollar. The decline comes despite the widely watched move by Washington to join Tokyo in supporting the currency. Less than two weeks after the US-Japan intervention, the yen has given up roughly half of its gains, raising fresh questions over the effectiveness of coordinated efforts to stabilize the exchange rate.
Japan and the US had previously confirmed coordinated foreign exchange intervention to prop up the yen after the currency tumbled to a nearly 40-year low. At the time, some observers saw the move as potentially stabilizing the yen in the short term, although its longer-term impact remained uncertain. 
However, the subsequent market reaction suggests that even the short-term effect may have been limited. After strengthening to about 155 per dollar in the days following the intervention from above 163, the yen had slipped back above 159 by Wednesday, less than two weeks later.
Questions have emerged over whether further support for the yen may soon be needed, and whether Washington would consider stepping in again. The previous intervention was seen by some observers as a test of market confidence: the unusual coordinated move had the potential to influence market expectations and discourage bets against the yen. But if market expectations remain largely unchanged, repeated interventions could deliver diminishing returns. The US may face a difficult trade-off. Another intervention could require greater resources and come at a higher cost, while refraining from further action could raise questions over the lasting impact of the previous effort.
Market commentary has added to the uncertainty. Axios published a report headlined "Yen's weakness shows market isn't done pushing," while some reports suggested that the impact of the US-Japan intervention was beginning to fade. Such narratives could weigh on sentiment toward the yen and reinforce market expectations that the currency's weakness may persist.
Washington's involvement in supporting the yen may reflect broader economic and policy considerations. These could include avoiding a scenario in which Japan sells US Treasury holdings to support the currency, as well as concerns that a weaker yen could give Japanese exporters a greater competitive advantage. These possible considerations suggest that the intervention alone does not fully address the underlying forces behind the yen's weakness. This may help explain why the market has so far been reluctant to view the move as a turning point for the currency.
Washington's decision to join the intervention may have reflected concerns, as some observers suggest, that the yen's prolonged weakness had begun to affect US interests. If markets remain unconvinced by the US-Japan intervention, one possible outcome is that Washington could push Japan to take more costly measures to support the yen. Such a scenario could instead create some strain between Washington and Tokyo.
Beyond short-term market dynamics, the yen's weakness also reflects deeper challenges facing the Japanese economy, making a sustained reversal difficult. The currency's prolonged weakness has been influenced by the interest rate gap between Japan and the US, while also reflecting longer-term concerns over the diminishing returns of Japan's traditional growth model.
This leaves Japan facing a delicate policy balance between supporting growth and stabilizing the currency. While lower interest rates could help boost economic activity, continued weakness in the yen may strengthen calls for Japan's central bank to consider further rate increases to narrow the interest rate gap with the US.
Japan's structural challenges mean that a sustained appreciation of the yen will not be easy to achieve. The question of whether to pursue stronger measures, even at the cost of some economic growth, has become more complicated as the US takes a role in the issue. Japan may face greater pressure to support the currency, even though doing so would be difficult and could carry broader economic costs.
The author is a reporter with the Global Times. [email protected]

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