Rice method is first to yield cartilage-like cells, engineer human cartilage
HOUSTON, Sept. 6, 2007 – Rice University biomedical engineers have developed a new technique for growing cartilage from human embryonic stem cells, a method that could be used to grow replacement cartilage for the surgical repair of knee, jaw, hip, and other joints.
“Because native cartilage is unable to heal itself, researchers have long looked for ways to grow replacement cartilage in the lab that could be used to surgically repair injuries,” said lead researcher Kyriacos A. Athanasiou, the Karl F. Hasselmann Professor of Bioengineering. “This research offers a novel approach for producing cartilage-like cells from embryonic stem cells, and it also presents the first method to use such cells to engineer cartilage tissue with significant functional properties.”
The results are available online and slated to appear in the September issue of the journal Stem Cells. The study involved cells from an NIH-sanctioned stem cell line.
Using a series of stimuli, the researchers developed a method of converting the stem cells into cartilage cells. Building upon this work, the researchers then developed a process for using the cartilage cells to make cartilage tissue. The results show that cartilages can be generated that mimic the different types of cartilage found in the human body, such as hyaline articular cartilage — the type of cartilage found in all joints — and fibrocartilage — a type found in the knee meniscus and the jaw joint. Athanasiou said the results are exciting, as they suggest that similar methods may be used to convert the stem cell-derived cartilage cells into robust cartilage sections that can be of clinical usefulness.
Tissue engineers, like those in Athanasiou’s research group, are attempting to unlock the secrets of the human body’s regenerative system to find new ways of growing replacement tissues like muscle, skin, bone and cartilage. Athanasiou’s Musculoskeletal Bioengineering Laboratory at Rice University specializes in growing cartilage tissues.
The idea behind using stem cells for tissue engineering is that these primordial cells have the ability to become more than one type of cell. In all people, there are many types of “adult” stem cells at work. Adult stem cells can replace the blood, bone, skin and other tissues in the body. Stem cells become specific cells based upon a complex series of chemical and biomechanical cues, signals that scientists are just now starting to understand.
Unlike adult stem cells, which can become only a limited number of cell types, embryonic stem cells can theoretically become any type of cell in the human body.
Athanasiou’s group has been one of the most successful in the world at studying cartilage cells and, especially, engineering cartilage tissues. He said that for his research the primary advantage that embryonic stem cells have over adult stem cells is their ability to remain malleable.
“Identifying a readily available cell source has been a major obstacle in cartilage engineering,” Athanasiou said. “We know how to convert adult stem cells into cartilage-like cells. The more problematic issue comes in trying to maintain a ready stock of adult stem cells to work with. These cells have a strong tendency to convert from stem cells into a more specific type of cell, so the clock is always ticking when we work with them.”
By contrast, Athanasiou said his research group has found it easier to grow and maintain a stock of embryonic stem cells. Nonetheless, he is quick to point out that there is no clear choice about which type of stem cell works best for cartilage engineering.
“We don’t know the answer to that,” Athanasiou said. “It’s extremely important that we study all potential cell candidates, and then compare and contrast those studies to find out which works best and under what conditions. Keep in mind that these processes are very complicated, so it may well be that different types of cells work best in different situations.”
Athanasiou began studying embryonic stem cells in 2005. Since funding for the program was limited, he asked two new graduate students in his group if they were interested in pursuing the work as a secondary project to their primary research. Those students, Eugene Koay and Gwen Hoben, are co-authors of the newly published study. Both are enrolled in the Baylor College of Medicine Medical Scientist Training Program, a joint program that allows students to concurrently earn their medical degree from Baylor while undertaking Ph.D. studies at Rice.
“Eugene and Gwen are both outstanding students,” Athanasiou said. “Each earned their undergraduate degree from Rice and each worked in my laboratory as undergraduate students. They have chosen to do this research because they think this may represent the future of regenerative medicine.”
The research was funded by Rice University.
Contact: Jade Boyd
Smoking shortens nap time of breastfed babies
PHILADELPHIA (September 4, 2007) – – A study from the Monell Chemical Senses Center reports that nicotine in the breast milk of lactating mothers who smoke cigarettes disrupts their infants’ sleep patterns.
“Infants spent less time sleeping overall and woke up from naps sooner when their mothers smoked prior to breastfeeding,” says lead author Julie A. Mennella, PhD, a psychobiologist at Monell.
The findings, published in the journal Pediatrics, raise new questions regarding whether nicotine exposure through breast milk affects infant development.
While many women quit or cut down on smoking while pregnant, they often relapse following the birth of the baby. Mennella comments, “Because nicotine is not contraindicated during lactation, mothers may believe that smoking while breastfeeding will not harm their child as long as the child is not exposed to passive smoke. However, there has been very little research on either short- or long-term effects of nicotine delivered through breast milk.”
Nicotine is a pharmacological stimulant that affects the developing brain and has been shown to cause long-term behavioral and learning deficits.
In the Monell study, researchers measured the feeding behavior and sleep patterns of 15 breastfed infants over a 3-1/2 hour observation period on two separate days. The infants were between two and seven months of age. All mothers were current smokers who abstained from smoking for at least 12 hours before each observation period.
Each mother smoked one to three cigarettes immediately prior to the observation period on one day and refrained from smoking on the other. On both occasions, mothers breastfed their infants on demand over the ensuing 3-1/2 hours. Following each feed, mothers laid infants down on their backs in a crib or on the floor.
An actigraph strapped to the infant’s ankle enabled researchers to measure activity and sleep time. Levels of nicotine and cotinine, a major metabolite of nicotine, were measured in breast milk samples provided by the mothers before each feed, allowing researchers to determine the dose of nicotine passed to each infant.
Total sleep time over the 3-1/2 hours declined from an average of 84 minutes when mothers refrained from smoking to 53 minutes on the day they did smoke, a 37% reduction in infant sleep time. This was due to a shortening of the longest sleep bout, or nap, and to reductions in the amount of time spent in both active and quiet sleep.
The level of sleep disruption was directly related to the dose of nicotine infants received from their mothers’ milk, consistent with a role for nicotine in causing the sleep disruptions.
Infants consumed the same amount of breast milk on both days, suggesting that they were accepting of tobacco flavor in breast milk. Previous research from Mennella’s laboratory has shown that infants demonstrate increased enjoyment of flavors experienced through transmission in breast milk.
Noting that children whose mothers smoke are more likely to smoke as teenagers, Mennella speculates that early experiences with tobacco flavor during breastfeeding may increase its appeal later in life.
She comments that additional studies are needed to examine the long-term developmental effects of nicotine delivered through breast milk.
An earlier study from Mennella’s lab demonstrated that breast milk nicotine levels peak 30 – 60 minutes after smoking one or two cigarettes and clear by three hours after the smoking episode. Emphasizing the many benefits of breastfeeding on infant health and development, Mennella notes that lactating mothers who smoke occasionally can time their smoking episodes to minimize nicotine exposure to their child.
The present findings highlight the need for targeted smoking cessation programs that address issues relevant to lactating women. Mennella suggests that concerns about tobacco flavor in their milk and disruptions of their infants’ sleep may help motivate breastfeeding mothers to abstain from smoking.
Lauren M. Yourshaw and Lindsay K. Morgan also contributed to the study.
The Monell Chemical Senses Center is a nonprofit basic research institute based in Philadelphia, Pennsylvania. For 39 years, Monell has been the nation’s leading research center focused on understanding the senses of smell, taste and chemical irritation: how they function and affect lives from before birth through old age. Using a multidisciplinary approach, scientists collaborate in the areas of: sensation and perception, neuroscience and molecular biology, environmental and occupational health, nutrition and appetite, health and well being, and chemical ecology and communication. For more information about Monell, visit http://www.monell.org.
FUNDING: National Institute on Alcohol Abuse and Alcoholism (NIH) and the Pennsylvania Department of Health. The Pennsylvania Department of Health specifically disclaims responsibility for any analyses, interpretations, or conclusions.
Contact: Leslie Stein
Monell Chemical Senses Center
Heidelberg, 8 August 2007
Socioeconomic status, and unemployment rates in particular, predict both the type of trauma seen in emergency rooms and the population groups more likely to be victims of trauma, according to Atul Madan (1) from the University of Tennessee Health Science Center and his team. Their findings have just been published online in Springer’s World Journal of Surgery.
The researchers looked at the link between unemployment rates and the types of trauma admissions in New Orleans over six years. Unemployment rates were obtained from the Bureau of Labor Statistics. The trauma registry of the Medical Center of Louisiana at New Orleans (Charity Hospital) provided data on the trauma emergency room admissions, including patient demographics.
Between January 1994 and November 1999, there were over 24,000 trauma admissions. During that period, the higher the unemployment rate, the higher the number of admissions for penetrating trauma – injuries that occur primarily by an object piercing the skin or entering a tissue of the body, such as bullets and knives.
The lower the unemployment rates, the higher the number of admissions for blunt trauma – physical trauma caused to a body part, either by impact, injury of physical attack which can result in contusions, abrasions, lacerations and bone fractures. In this instance, the majority of blunt trauma was the result of motor vehicle collisions. The authors suggest that a possible explanation for this surprising finding could be the fact that with higher incomes, more travel is likely, which in turn increases the likelihood of motor vehicle collisions. Alternatively, more tourism to the area may have reduced unemployment but caused more road accidents.
The study also shows that as the socioeconomic status, measured here by unemployment rates, of the community changes, so do the demographics and mortality rates of the trauma population. There were more male patients, African American patients and deaths at times of high unemployment. These results suggest that during times of economic hardship, certain population groups are at higher risk of life-threatening injuries.
The authors recommend that “injury prevention efforts targeted at economically disadvantaged populations and high-risk groups should be stressed when designing community trauma outreach programs, especially during times of economic hardships.”
(1) Madan A et al (2007). Unemployment rates and trauma admissions. World Journal of Surgery (DOI 10.1007/s00268-007-9190-4)
In spite that the causes of depression have not still been fully identified, scientists acknowledge that genetic and environmental factors play a common role in the onset of this disorder. One of the environmental risk factors more often related to depression is exposure to threatening life events. On the other side, from a genetic point of view, the serotonin transporter gene, with a crucial role in communication between neurons, could predispose to depression.
An international group of scientists, headed by professors Jorge Cervilla Ballesteros and Blanca Gutiérrez Martínez, from the department of Legal Medicine, Toxicology and Psychiatry of the University of Granada, has recently published in the prestigious journal Molecular Psychiatry the pioneering study PREDICT-gene, confirming the relation between allele s in the serotonin transporter gene and exposure to threatening life events in the onset of depression. The study proves, for a population sample accounting for gender, age and family history of psychiatric disorders, that 24% of the Spanish population, comprising people with the s/s genotype, need minimal exposure to threatening life events, unlike individuals with s/l or l/l genotypes, thus confirming the relation between genetic and environmental factors in this mental disorder.
The most important consequence of research on interaction between genetic and environmental factors is that, in a foreseeable future, scientists will be able to produce measures to predict response to antidepressants taking into account each individual’s genotype, i. e. they will be able to design tailor-made drugs according to each person’s genetic configuration and their exposure to environmental factors.
The research group headed by professor Cervilla Ballesteros and Gutiérrez Martínez is currently working at the University of Granada to open roads for psycho-pharmaco-genetics, a field that will allow for individual treatments, tailor-made drugs, for each patient with depression, a disorder affecting one in every five Spaniards visiting the doctor’s.
This study is framed in the international project PREDICT and is funded by the European Union and the Spanish Ministry of Education and Science. One of its most important novelties is that it has been carried out through a very representative sample: a total of 737 people agreed to participate in the genetic tests, with ages ranging from 18 to 75, patients of nine primary care centres in the South of Spain. That is why this is the first representative population-based replication of earlier research, as until now research had been done into restricted population samples, comprising only women, adolescents, twins or people with affective disorders.
Contact: Professor Jorge Cervilla Ballesteros
Universidad de Granada
The most accurate measures of European daily temperatures ever indicate that the length of heat waves on the continent has doubled and the frequency of extremely hot days has nearly tripled in the past century. The new data shows that many previous assessments of daily summer temperature change underestimated heat wave events in western Europe by approximately 30 percent.
Paul Della-Marta and a team of researchers at the University of Bern in Switzerland compiled evidence from 54 high-quality recording locations from Sweden to Croatia and report that heat waves last an average of 3 days now—with some lasting up to 4.5 days—compared to an average of around 1.5 days in 1880. The results are published 3 August in the Journal of Geophysical Research-Atmospheres, a publication of the American Geophysical Union. The researchers suggest that their conclusions contribute to growing evidence that western Europe’s climate has become more extreme and confirm a previously hypothesized increase in the variance of daily summer temperatures since the 19th century.
The study adds evidence that heat waves, such as the devastating 2003 event in western Europe, are a likely sign of global warming; one that perhaps began as early as the 1950s, when their study showed some of the highest trends in summer mean temperature and summer temperature variance.
“These results add more evidence to the belief among climate scientists that western Europe will experience some of the highest environmental and social impacts of climate change and continue to experience devastating hot summers like the summer of 2003 more frequently in the future,” Della-Marta said.
The authors note that temperature records were likely overestimated in the past, when thermometers were not kept in modern Stevenson screens, which are instrument shelters used to protect temperature sensors from outside influences that could alter its readings. The researchers corrected for this warm bias and other biases in the variability of daily summer temperatures and show that nearly 40 percent of the changes in the frequency of hot days are likely to be caused by increases in summer temperatures’ variability. This finding demonstrates that even a small change in the variance of daily summer temperatures can radically enhance the number of extremely hot days.
“These findings provide observational support to climate modeling studies showing that European summer temperatures are particularly sensitive to global warming,” Della-Marta said. “Due to complex reactions between the summer atmosphere and the land, the variability of summer temperatures is expected to [continue to] increase substantially by 2100.”
The research was supported by the European Environment and Sustainable Development Program, the Swiss National Science Foundation and the National Center for Excellence in Climate Research (NCCR Climate).
Contact: Jonathan Lifland
American Geophysical Union
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