Artificial Skin Created Using Umbilical Cord Stem Cells


Major burn patients usually must wait weeks for artificial skin to be grown in the laboratory to replace their damaged skin, buy a Spanish laboratory has developed new protocols and techniques that accelerate the growth of artificial skin from umbilical cord stem cells. Such laboratory-grown skin can be frozen and stored in tissue banks and used when needed.

Growing skin in the laboratory requires the acquisition of keratinocytes, those cells that compose the skin and the mucosal covering inside our mouths.  Keratinocytes can be cultured in the laboratory, but they have a long cell cycle, which means that they take a really long time to divide.  Consequently, cell cultures of keratinocytes tend to take a very long time to grow.

Keratinocytes in culture
Keratinocytes in culture

As they grow, the keratinocytes respond to connective tissue underneath them to receive the cues that tell them how to connect with each other and form either skin or oral mucosa.  In patients with severe burns, however, the underlying connective tissue is also often damaged.  Therefore, finding a way to not only accelerate the growth of cultured keratinocytes, but also to provide the underlying structure that directs the cells to form a proper epithelium is essential.

Remember that severe burn patients are living on borrowed time.  Without a proper skin covering, water loss is severe and dehydration is a genuine threat.  Also, infection is another looming threat.  Therefore, the treatment of a burn patient is a race against time.

Because umbilical cord stem cells grow quickly and effectively in culture, they might be able to differentiate into keratinocytes and form the structures associated with oral mucosa and skin.

University of Granada researchers used a new type of epithelial covering to grow their artificial skin in addition to a biomaterial made of fibrin (the stiff, cable-like protein that forms clots) and agarose to provide the underlying connective tissue. In case you might need a refresher, an epithelium refers to a layer of cells that have distinct connects with each other and form a discrete layer. Epithelia can form single or multiple layers and can be composed of long, skinny cells, short, flat cells, or boxy cells.  An epithelium is a membrane-like tissue composed of one or more layers of cells separated by very little intervening substances.  Epithelia cover most internal and external surfaces of the body and its organs.

Previous work from this same research group showed that stem cells from Wharton’s jelly (connective tissue within the umbilical cord), could be converted into epithelial cells. This current study confirms and extends this previous work and applies it to growing skin, and oral mucosa.

“Creating this new type of skin suing stem cells, which can be stored in tissue banks, mains that it can be used instantly when injuries are caused, and which would bring the application of artificial skin forward many weeks,” said Antonio Campos, professor of histology and one of the authors of this study.

By growing the Wharton’s jelly stem cells on their engineered matrix in a three-dimensional culture system, Campos and his colleagues saw that the stem cells stratified (formed layers), and expressed a bunch of genes that are peculiar to skin and other types of epithelia that cover surfaces (e.g., cytokeratins 1, 4, 8, and 13; plakoglobin, filaggrin, and involucrin).  When examined with an electron microscope, the cells had truly formed the kinds of tight connections and junctions that are so common to skin epithelia.

Electron microscopy analysis of controls and three-dimensional bioactive models of H-hOM and H-hS. SEM images (top) corresponding to N-hOM and N-hS controls showed a tight superficial layer of flat polygonal cells with desquamation signs in which cells were covering the entire surface, whereas samples kept in vitro for 2 weeks showed immature differentiation patterns, and samples implanted in vivo for 40 days tended to resemble the structure of the native control tissues, with flattened cells and evident signs of desquamation. Scale bars = 50 μm. TEM samples (bottom) were analyzed after 40 days of in vivo implantation and demonstrated that in vivo-implanted tissues were mature and well-differentiated, with numerous intercellular junctions, abundant cell organelles, and a collagen-rich stroma. Scale bars = 1 μm. Abbreviations: H-hOM, heterotypical human oral mucosa; H-hS, heterotypical human skin; N-hOM, native human oral mucosa; N-hS, native human skin; SEM, scanning electron microscopy; TEM, transmission electron microscopy.
Electron microscopy analysis of controls and three-dimensional bioactive models of H-hOM and H-hS. SEM images (top) corresponding to N-hOM and N-hS controls showed a tight superficial layer of flat polygonal cells with desquamation signs in which cells were covering the entire surface, whereas samples kept in vitro for 2 weeks showed immature differentiation patterns, and samples implanted in vivo for 40 days tended to resemble the structure of the native control tissues, with flattened cells and evident signs of desquamation. Scale bars = 50 μm. TEM samples (bottom) were analyzed after 40 days of in vivo implantation and demonstrated that in vivo-implanted tissues were mature and well-differentiated, with numerous intercellular junctions, abundant cell organelles, and a collagen-rich stroma. Scale bars = 1 μm. Abbreviations: H-hOM, heterotypical human oral mucosa; H-hS, heterotypical human skin; N-hOM, native human oral mucosa; N-hS, native human skin; SEM, scanning electron microscopy; TEM, transmission electron microscopy.

The authors conclude the article with this statement: “All these findings support the idea that HWJSCs could be useful for the development of human skin and oral mucosa tissues for clinical use in patients with large skin and oral mucosa injuries.”  Think of it folks – new skin for burn patients, quickly, safely and ethically.

Now back to reality – this is exciting, but it is a a pre-clinical study.  Larger animals studies must show the efficacy and safety of this protocol before human trials can be considered, but you must admit that it looks exciting; and without killing any embryos.

See I. Garzón, et al., Stem Cells Trans MedAugust 2013 vol. 2 no. 8625-632.

A Molecular Switch that Causes Stem Cell Aging


A study from the Cincinnati Children’s Hospital Medical Center, in collaboration with the University of Ulm in Germany has discovered a molecular switch that causes the aging of blood stem cells. This same work suggests a therapeutic strategy to delay stem cell aging.

Hematopoietic stem cells (HSCs) reside in the bone marrow and make all the red and white blood cells that populate the bloodstream. Proper HSC function is absolutely vital to the ongoing production of different types of blood cells that allow the immune system to fight infections and organs to receive adequate quantities of oxygen.

Hartmut Geiger from the Cincinnati Children’s Hospital Medical Center and the University of Ulm was the senior researcher on this project. Dr. Geiger said, “Although there is a large amount of data showing that blood stem cell function declines during aging, the molecular processes that cause this remain largely unknown. This prevents rational approaches to attenuate stem cell aging. This study puts us significantly closer to that goal through novel findings that show a distinct switch in a molecular pathway is very critical to the aging process.”

The pathway to which Dr. Geiger referred is the Wnt signaling pathway, which plays a foundational role in animal development, cell-cell communication, tissue generation, and is also involved in the pathology of various diseases.

Crystal structure of XWnt8
Crystal structure of XWnt8

Analysis of mouse models and cultured HSCs showed that under normal conditions, Wnt signaling in HSCs occurred through the so-called “canonical” Wnt signaling pathway. The canonical Wnt signaling pathway utilizes the typical components of Wnt signaling that were first identified in the fruit fly and then isolated and characterized in vertebrates (shown below).

Canonical Wnt signaling

However, Wnt proteins can also signaling through other, distinct signal transduction pathways, and these types of pathways are collectively known as “noncanonical” Wnt signaling pathway. In aging HSCs, a switch from canonical Wnt signaling to noncanonical Wnt signaling marked the onset of HSC aging.  See below for one example of non-canonical Wnt signaling.

Non-canonical Wnt signaling

To test this observation, Geiger’s group overexpressed Wnt5 in HSCs (a Wnt protein known to induced signaling through noncanonical Wnt signaling pathways), and immediately, the HSCs began to show the signs of aging.

One of the targets of Wnt5 signaling is a protein called Cdc42, which influences the cytoskeleton of cells.  Therefore, Geiger and his crew asked if Cdc42 was activated in those HSCs that overexpressed Wnt5.  The answer to this question was a clear “yes.”  Then they treated cultured HSCs with a molecule that inhibited Cdc42 activity.  This treatment reversed the aging process in HSCs.

To test their hypothesis in a living animal, Geiger and others removed a copy of the Wnt5 gene from HSCs in laboratory mice.  Mice that lacked functional Wnt5 protein in HSCs, showed rejuvenation of the aged HSCs.  Mice that lacked both copies of the Wnt5 gene showed a delayed aging process in their HSCs.

Even though this study has definitely made an important contribution to understanding HSC aging, more work is needed before a therapeutic strategy is in place.

The Role of Astrocytes in Lou Gehring’s Disease


A study from Columbia University and Harvard University has uncovered a complex interplay between neurons and support cells known as astrocytes that contributes to the pathology of ALS. Such an intricate interplay complicates regenerative therapies for this disease.

In the spinal cord, a group of neurons called motor neurons extend their axons to skeletal muscles and provide the neural signals for the muscles to contract, which allows movement. Motor neurons also have associated support cells known as glial cells, and a specific group of glial cells known as astrocytes associate with motor neurons in the spinal cord.

Astrocytes are star-shaped cells that surround neurons in the brain and spinal cord, and they outnumber neurons 50:1. Astrocytes are very active in the central nervous system, and serve to maintain, support, and repair the nervous tissue that they serve, and are responsible, in large part, for the plasticity of the nervous system.

astrocytes1 (1)

Motor neurons die off during the course of ALS, which leads to paralysis and death within two to fives years of diagnosis. ALS also affects neurons in the brain and it completely robs the individual of the ability to initiate movement or even breathe. There is, at present, no cure and no life-prolonging treatment for ALS.

Data from the ALS Association group suggests that astrocytes in ALS patients go from supporting neurons to strangling them. According to Lucie Bruijn, the chief scientist at the ALS Association in Washington D.C.,, these results seem to “strengthen the case that astrocytes are central to the ALS disease process.” She continued: “Furthermore, the results are based on an exciting new disease model system, one that will allow us to test important hypotheses and search for new therapeutic targets.”

In a cell culture system of ALS, in which neurons derived from embryonic cells were co-cultured with normal and ALS astrocytes, Bruijn’s team found that gene expression patterns in those neurons associated with ALS astrocytes were abnormal. In this experiment, neurons derived from embryonic stem cells with co-cultured with normal and ALS affected astrocytes. In a time course experiment in which gene expression profiles were analyzed from the neurons after specific amounts of time, the gene expression patterns from the normal astrocytes co-cultured with neurons were compared with those of the ALS-affected astrocytes co-cultured with neurons. From these experiments, it became clear that the ALS-affected astrocytes did not communicate properly with the nearby neurons.

Even though neurons communicated with each other by means of the release of neurotransmitters, astrocytes and other glial cells also communicate with each other by means of the release of various molecules. This astrocyte-neuron communication maintains healthy neuron function. However, in the case of ALS, the neuron-astrocyte communication is “profoundly disrupted” and is disruption is not neuron dependent, since in this experiment, the neurons were normal. Without proper communication with their astrocytes, motor neurons the spinal cords of ALS patients are not able to function properly.

According to Bruijn, “This study points out several potential points for treatment intervention.” The protection of motor neurons is the goal, since the astrocytes seem to be doing little to protect and support the neurons and also might be hurting them.

An added bonus to this study is that when spinal cords from mice with a disease that shows some similarities to ALS have their gene expression profiles compared to these gene expression profiles observed in the cultured neurons, the results are remarkably similar. This shows that culture system does recapitulate what goes on in the spinal cord.

The next step is to show that the molecular abnormalities discovered in this system mimics those that occur in human disease. This publication utilized mouse cells, and the human disease, while similar, is not exactly the same.