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Welcome to The Visible Embryo, a comprehensive educational resource on human development from conception to birth.

The Visible Embryo provides visual references for changes in fetal development throughout pregnancy and can be navigated via fetal development or maternal changes.

The National Institutes of Child Health and Human Development awarded Phase I and Phase II Small Business Innovative Research Grants to develop The Visible Embryo. Initally designed to evaluate the internet as a teaching tool for first year medical students, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than one million visitors each month.

Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
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Home | Pregnancy Timeline | News Alerts |News Archive Sep 6, 2013

 






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Youthful stem cells from bone can heal the heart

Findings raise hope for new heart therapies from stem cells found in cortical, or compact, bone.

Many people who survive a heart attack find themselves back in the hospital with a failing heart just years later. And the outcome often is unfavorable, owing to limited treatment options. But scientists at Temple University School of Medicine's Cardiovascular Research Center (CVRC) recently found hope in an unlikely source – stem cells in cortical, or compact, bone. In a new study, they show that when it comes to the regeneration of heart tissue, these novel bone-derived cells do a better job than the heart's own stem cells.

According to the study's senior investigator, Steven R. Houser, Ph.D., FAHA, Chairperson of Temple's Department of Physiology and Director of the CVRC, it is early days for cortical bone-derived stem cells (CBSCs). Nonetheless, his team's findings, featured on the cover of the August 16th issue of Circulation Research, have considerable implications for stem cell therapy for the heart.

A major challenge in the treatment of heart attack is early intervention, which is key to reducing the chances for long-term complications, such as heart failure. When it comes to stem cells, Houser said, "The strategy is to inject the cells right after [a heart attack]." Currently, though, that approach works only in animal studies. To make it work in humans, Houser explained, "we need cells right off the rack and ready to go clinically."

CBSCs could be those cells.


Stem cells are youthful by degrees, and cortical bone-derived stem cells—CBSCs—are considered some of the most pluripotent, like human newborns, naïve and ready to become anything.

But while CBSCs and similarly pluripotent stem cells retain the ability to develop into any cell type needed by the body and sometimes bring their youthful energy to the aid of mature cells—making them especially appealing for therapeutics—they also have the potential to wander off course, possibly landing themselves in unintended tissues.

Cardiac stem cells, on the other hand, are a little more capable and a little more set in their ways, like toddlers. While they may need some coaxing into action, they are more likely to stay in their resident tissue.


To figure out how CBSCs might behave in the heart in the first place, Houser's team, led by Temple graduate student Jason Duran, began by collecting the cells from mouse tibias. The particular mice used had been engineered with green fluorescent protein (GFP), which meant that the CBSCs carried a green marker to allow for their later identification. The cells were then expanded in petri dishes in the laboratory before being injected directly into the hearts of non-GFP mice that had suffered heart attacks. Some mice received cardiac stem cells instead of CBSCs.

In the following weeks, as the team monitored the progress of the mice, they found that the youthfulness of the CBSCs had prevailed. The cells had triggered the growth of new blood vessels in the injured tissue, and six weeks after injection, they had differentiated, or matured, into heart muscle cells. While generally smaller than native heart cells, the new cells had the same functional capabilities, and overall they had improved survival and heart function. Similar improvements were not observed in the subset of mice treated with cardiac stem cells. Nor was there evidence in those mice that the cardiac cells had undergone differentiation.

The findings challenge the general assumption that cardiac stem cells, because they reside in the heart, are the cells most capable of repairing damaged heart tissue. For that reason, according to Houser, the new paper likely will be controversial.

Houser: "What we did generates as many questions as it does answers. Cell therapy attempts to repopulate the heart with new heart cells. But which cells should be used, and when they should be put into the heart are among many unanswered questions."

To address at least some of those questions, Houser's team plans next to investigate CBSCs in a large-animal heart attack model. If that study yields similar results as the first, the cells could be ushered into a small-scale clinical trial of human patients.


In humans, CBSCs would be collected from bone using techniques akin to those employed for bone marrow aspiration, a much simpler process than that used to isolate cardiac stem cells.

While the cells would originate from a different person, raising the risk of rejection by the patient's immune system, it may be possible to have them at the ready in hospital settings, allowing for their injection immediately after a heart attack.


The cell therapy work by Houser's team represents just one of several forms of heart therapy being explored at Temple's CVRC. According to Houser, "Temple has made a commitment to cardiovascular research, with a clinical enterprise focused on treating patients. We're trying anything and everything to repair the heart [safely]." Other avenues of research include gene therapy, drug therapy, and the use of novel biomaterials to more effectively deliver drugs.

Abstract
Rationale: Autologous bone marrow–derived or cardiac-derived stem cell therapy for heart disease has demonstrated safety and efficacy in clinical trials, but functional improvements have been limited. Finding the optimal stem cell type best suited for cardiac regeneration is the key toward improving clinical outcomes.

Objective: To determine the mechanism by which novel bone-derived stem cells support the injured heart.

Methods and Results: Cortical bone–derived stem cells (CBSCs) and cardiac-derived stem cells were isolated from enhanced green fluorescent protein (EGFP+) transgenic mice and were shown to express c-kit and Sca-1 as well as 8 paracrine factors involved in cardioprotection, angiogenesis, and stem cell function. Wild-type C57BL/6 mice underwent sham operation (n=21) or myocardial infarction with injection of CBSCs (n=67), cardiac-derived stem cells (n=36), or saline (n=60). Cardiac function was monitored using echocardiography. Only 2/8 paracrine factors were detected in EGFP+ CBSCs in vivo (basic fibroblast growth factor and vascular endothelial growth factor), and this expression was associated with increased neovascularization of the infarct border zone. CBSC therapy improved survival, cardiac function, regional strain, attenuated remodeling, and decreased infarct size relative to cardiac-derived stem cells– or saline-treated myocardial infarction controls. By 6 weeks, EGFP+ cardiomyocytes, vascular smooth muscle, and endothelial cells could be identified in CBSC-treated, but not in cardiac-derived stem cells–treated, animals. EGFP+ CBSC-derived isolated myocytes were smaller and more frequently mononucleated, but were functionally indistinguishable from EGFP− myocytes.

Conclusions: CBSCs improve survival, cardiac function, and attenuate remodeling through the following 2 mechanisms: (1) secretion of proangiogenic factors that stimulate endogenous neovascularization, and (2) differentiation into functional adult myocytes and vascular cells.

Other researchers contributing to the work include Catherine A. Makarewich, Thomas E. Sharp, Timothy Starosta, Yumi Chiba, Remus M. Berretta, and Hajime Kubo, at the Cardiovascular Research Center at Temple; Nicholas E. Hoffman and Muniswamy Madesh, at the Center for Translational Medicine at Temple; and Fang Zhu, at the Biostatistics and Bioinformatics Facility, Fox Chase Cancer Center.

The research was supported in part by NIH grants R01HL089312, T32HL091804, P01HL091799, and R37HL033921.

About Temple Health
Temple Health refers to the health, education and research activities carried out by the affiliates of Temple University Health System and by Temple University School of Medicine.

Temple University Health System (TUHS) is a $1.4 billion academic health system dedicated to providing access to quality patient care and supporting excellence in medical education and research. The Health System consists of Temple University Hospital (TUH), ranked among the "Best Hospitals" in the region by U.S. News & World Report; TUH-Episcopal Campus; TUH-Northeastern Campus; Fox Chase Cancer Center, an NCI-designated comprehensive cancer center; Jeanes Hospital, a community-based hospital offering medical, surgical and emergency services; Temple Transport Team, a ground and air-ambulance company; and Temple Physicians, Inc., a network of community-based specialty and primary-care physician practices. TUHS is affiliated with Temple University School of Medicine.

Temple University School of Medicine (TUSM), established in 1901, is one of the nation's leading medical schools. Each year, the School of Medicine educates approximately 840 medical students and 140 graduate students. Based on its level of funding from the National Institutes of Health, Temple University School of Medicine is the second-highest ranked medical school in Philadelphia and the third-highest in the Commonwealth of Pennsylvania. According to U.S. News & World Report, TUSM is among the top 10 most applied-to medical schools in the nation.

Original press release:http://www.templehealth.org/content/newsroom.htm?page_id=11&minor=
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