Imagine entering the world with a silent, permanent biological vulnerability that might not surface until decades later. For the 15 million babies—roughly one in ten births—born prematurely each year, this is the hidden reality of kidney health. While scientists have long known that preterm birth doubles the lifetime risk of chronic kidney disease, the precise biological mechanism behind this vulnerability remained elusive until now.
Prematurity is defined as a live birth occurring before 37 weeks of gestation. Thanks to advances in neonatal care and medical research, the survival rate of premature infants has risen significantly in recent decades. However, surviving preterm babies often face a heightened risk of developing chronic illnesses in adulthood, particularly when vital organs like the kidneys do not fully mature in the womb.
A landmark collaborative study by researchers at Hadassah-University Medical Center in Jerusalem’s Ein Kerem and Monash University in Melbourne has finally revealed the cellular mechanism behind this vulnerability. Crucially, the research has identified a narrow therapeutic window during which early interventions could protect these fragile organs for a lifetime—long before clinical symptoms ever manifest.
The research was led by Dr. Morris Nechama of Hadassah’s pediatric nephrology unit and the Faculty of Medicine at the Hebrew University of Jerusalem, alongside Athar Amleh, a doctoral researcher from the Palestinian Authority whose studies at Hadassah are supported by the Yad Hanadiv Foundation.
Published in iScience under the title “Preterm birth disrupts nephron progenitor cell dynamics predisposing to renal disease,” this groundbreaking paper provides the definitive explanation of why the kidneys of premature infants remain vulnerable to lifelong damage.
Using an advanced mouse model of preterm birth, the research team pinpointed the exact cellular disruptions caused by early delivery that restrict the formation of kidney filtration units. This discovery highlights a critical, narrow window of opportunity during which future preventative therapies must be administered to safeguard renal development.
A healthy human kidney relies on approximately one million microscopic filtration units, known as nephrons, which are established entirely before or around birth and are never regenerated. This study reveals for the first time how premature birth disrupts this delicate developmental timeline, leaving millions of adults with a diminished kidney reserve that goes unnoticed until health declines.
The underlying cellular mechanism results in too few filtration units, coupled with an extremely brief window for potential intervention. The researchers suggest that these findings could pave the way for clinical strategies designed to protect the kidneys of premature babies from the very beginning of their lives.
“We have long been aware that children born prematurely enter adulthood with kidneys that are far more vulnerable to disease, but the exact biological failure and its timing remained a mystery,” Dr. Nechama explained. “In our study, we observed this process unfold in real time. Within just hours of premature birth, nephron progenitor cells enter a state of severe distress, and their developmental timing is thrown off. They attempt to compensate later, but by then, the critical window for development has already closed.”
Health effects from premature birth
In a longitudinal American study tracking teenagers who were born prematurely, approximately half already exhibited early signs of kidney distress, including high blood pressure, protein in the urine, or abnormally small kidneys. Consequently, many individuals navigate adulthood with a reduced renal reserve, entirely unaware of their vulnerability until clinical complications arise.
A healthy kidney consists of roughly one million tiny filtration units called nephrons. The formation of these nephrons is typically completed by the 35th week of gestation, though the final count varies significantly from person to person. Because nephrons do not regenerate after birth, individuals born with fewer nephrons carry a permanently reduced kidney reserve throughout their entire lives, as Dr. Oded Volovelsky noted in an interview with The Jerusalem Post.
Preterm birth is increasingly recognized not just as an acute neonatal event, but as a lifelong determinant of overall renal health. However, the specific cellular and molecular mechanisms driving this developmental programming have remained difficult to isolate, particularly in clinical settings where patients often present with multiple concurrent conditions—such as sepsis, nephrotoxic medications, or postnatal steroid treatment—that independently affect kidney function.
The nephron is the fundamental functional unit of the kidney, responsible for filtering blood, removing waste products, and producing urine. Currently, there are no clinical interventions capable of increasing the total number of nephrons in a human kidney.
Epidemiological data have consistently shown that children and adults born prematurely experience higher rates of hypertension, proteinuria, and diminished kidney function. Until this research, the precise biological explanation for these clinical observations remained unknown.
“Our research, utilizing a mouse model of preterm birth, provides the long-awaited answer,” Dr. Volovelsky added. “By examining the progenitor cells responsible for generating nephrons, we found that the sudden, early transition from the womb to the outside world disrupts the precise timing of their development and maturation. The cells immediately enter a state of severe stress, losing the opportunity for proper repair. We believe these mechanistic insights are highly relevant to human infants.”
“Immediately following premature birth, the progenitor cells experience severe cellular stress, triggering an emergency molecular pathway known as the unfolded protein response. Concurrently, the genes responsible for differentiating into mature nephrons are suppressed. In essence, the cells redirect their focus from active construction to mere survival.”
A day later, the cells attempt to compensate for this delay through a rapid wave of division and differentiation. However, this corrective response inevitably arrives too late to recover the lost developmental ground.
“One of the most surprising findings in our study is that in preterm animals, the period of nephron formation extends by approximately 24 hours compared to normal development. Yet, this extension fails to bridge the deficit. The ultimate result is a permanent nephron shortfall, which is clearly measurable by one month postnatal and is already accompanied by early signs of declining kidney function,” Dr. Volovelsky noted.
In subsequent examinations conducted at an age equivalent to human adulthood, the kidneys of these mice displayed clear signs of chronic damage: the glomeruli had enlarged in an attempt to compensate for their scarcity, protein was detected in their urine, and markers of tubular damage had accumulated. In other words, the cellular damage initiated in the first few days of life continues to unfold and worsen over the span of decades.
“In our clinical practice, we follow children born prematurely and witness the consequences years later, often manifesting only in adolescence. This study highlights that the first few days after birth are not merely a period of survival, but a critical window during which the lifelong renal reserve is established. This perspective fundamentally shifts how we should monitor and screen these children. Premature infants should undergo long-term monitoring for kidney health as they grow older.”
An additional finding highlighted a significant gender disparity. “The impairment in nephron count and overall kidney function was pronounced in males but not in females. This aligns with previous evidence suggesting that male fetuses are more vulnerable to adverse perinatal conditions, and it may assist in future clinical risk assessments,” the pediatric nephrologist noted.
Identifying the cellular stress response as the primary point of failure suggests a highly practical intervention window in the immediate days following premature birth. If this molecular stress response can be safely suppressed or managed in time, it may be possible to preserve a significant portion of the nephrons that are currently lost.
The researchers emphasize that while this study successfully identifies the underlying mechanism and critical timing, it represents an early stage of investigation. A clinical treatment designed to prevent this damage has not yet been tested, which remains the primary objective of their subsequent research.
Dr. Nechama and Dr. Volovelsky believe their research could eventually revolutionize the management and care of kidney disease. The possibility of restoring nephron numbers through timely, targeted interventions in experimental models offers new hope for the global struggle to prevent and treat chronic kidney diseases.
This study emerged from an Israeli-Australian collaborative initiative supported by AUSiMED, an Australian charity dedicated to fostering joint medical research between the two nations.
Despite the challenges of ongoing conflict, the collaboration proceeded without interruption. Laboratory operations in Jerusalem and bioinformatic analyses in Melbourne ran in parallel, maintained through daily coordination across time zones and complex security conditions. For the research teams, this relentless cooperation served as a powerful testament to the resilience of international medical science under the most difficult circumstances.
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