Harvesting the potential of the human umbilical cord: isolation and characterisation of four cell types for tissue engineering applications

Vasorelaxant effect of phenylpropanoids: Methyl eugenol and eugenol in human umbilical cord vein

Methyl-eugenol (ME) and eugenol (EUG) are phenylpropanoids with vasodilatory effects. While EUG's vasorelaxant effect in human umbilical artery (HUA) is known, their action in veins is unclear. This study aimed to evaluate ME and EUG in human umbilical vein (HUV). Isolated HUV underwent tension recordings. ME and EUG caused 100 % relaxation in HUV, with EC50 values corresponding to: 174.3 ± 7.3 and 217.3 ± 6.2 µM for ME and EUG respectively in presence of K+; 362.3 ± 5.4 and 227.7 ± 4.9 µM for ME and EUG respectively and in presence of serotonin (5-HT). It was observed that in presence of BaCl2 and CaCl2 evoked contractions, ME (800 and 1000 µM) and EUG (1000 and 1400 µM) prevent the contractions. In presence of K+ channel blockers it was observed that ME promoted relaxation compared to its control, except in presence of 4-AP, suggesting a possible Ca2+-dependent K+ channel activation for this molecule; EUG increased all EC50 in presence of the K+ blockers except in presence of TEA 1 mM. Greater pharmacological potency was observed for ME. This study highlights natural substances' effects on HUV contractile parameters, suggesting ME and EUG as potential vasodilators in maintaining fetal oxygenation and venous flow during gestational hypertensive syndromes.

Woven bone formation and mineralization by rat mesenchymal stromal cells imply increased expression of the intermediate filament desmin

Background

Disordered and hypomineralized woven bone formation by dysfunctional mesenchymal stromal cells (MSCs) characterize delayed fracture healing and endocrine -metabolic bone disorders like fibrous dysplasia and Paget disease of bone. To shed light on molecular players in osteoblast differentiation, woven bone formation, and mineralization by MSCs we looked at the intermediate filament desmin (DES) during the skeletogenic commitment of rat bone marrow MSCs (rBMSCs), where its bone-related action remains elusive.

Results

Monolayer cultures of immunophenotypically- and morphologically - characterized, adult male rBMSCs showed co-localization of desmin (DES) with vimentin, F-actin, and runx2 in all cell morphotypes, each contributing to sparse and dense colonies. Proteomic analysis of these cells revealed a topologically-relevant interactome, focused on cytoskeletal and related enzymes//chaperone/signalling molecules linking DES to runx2 and alkaline phosphatase (ALP). Osteogenic differentiation led to mineralized woven bone nodules confined to dense colonies, significantly smaller and more circular with respect to controls. It significantly increased also colony-forming efficiency and the number of DES-immunoreactive dense colonies, and immunostaining of co-localized DES/runx-2 and DES/ALP. These data confirmed pre-osteoblastic and osteoblastic differentiation, woven bone formation, and mineralization, supporting DES as a player in the molecular pathway leading to the osteogenic fate of rBMSCs.

Conclusion

Immunocytochemical and morphometric studies coupled with proteomic and bioinformatic analysis support the concept that DES may act as an upstream signal for the skeletogenic commitment of rBMSCs. Thus, we suggest that altered metabolism of osteoblasts, woven bone, and mineralization by dysfunctional BMSCs might early be revealed by changes in DES expression//levels. Non-union fractures and endocrine - metabolic bone disorders like fibrous dysplasia and Paget disease of bone might take advantage of this molecular evidence for their early diagnosis and follow-up.

Tissue Engineering for Gastrointestinal and Genitourinary Tracts

The gastrointestinal and genitourinary tracts share several similarities. Primarily, these tissues are composed of hollow structures lined by an epithelium through which materials need to flow with the help of peristalsis brought by muscle contraction. In the case of the gastrointestinal tract, solid or liquid food must circulate to be digested and absorbed and the waste products eliminated. In the case of the urinary tract, the urine produced by the kidneys must flow to the bladder, where it is stored until its elimination from the body. Finally, in the case of the vagina, it must allow the evacuation of blood during menstruation, accommodate the male sexual organ during coitus, and is the natural way to birth a child. The present review describes the anatomy, pathologies, and treatments of such organs, emphasizing tissue engineering strategies.

Human Umbilical Cord Lining-Derived Epithelial Cells: A Potential Source of Non-Native Epithelial Cells That Accelerate Healing in a Porcine Cutaneous Wound Model

Human umbilical cord lining epithelial cells [CLECs) are naïve in nature and can be ethically recovered from cords that are routinely discarded. The success of using oral mucosal epithelial cells for cornea defects hints at the feasibility of treating cutaneous wounds using non-native CLECs. Herein, we characterized CLECs using flow cytometry (FC) and skin organotypic cultures in direct comparison with skin keratinocytes (KCs). This was followed by wound healing study to compare the effects of CLEC application and the traditional use of human skin allografts (HSGs) in a porcine wound model. While CLECs were found to express all the epidermal cell markers probed, the major difference between CLECs and KCs lies in the level of expression (in FC analysis) as well as in the location of expression (of the epithelium in organotypic cultures) of some of the basal cell markers probed. On the pig wounds, CLEC application promoted accelerated healing with no adverse reaction compared to HSG use. Though CLECs, like HSGs, elicited high levels of local and systemic immune responses in the animals during the first week, these effects were tapered off more quickly in the CLEC-treated group. Overall, the in vivo porcine data point to the potential of CLECs as a non-native and safe source of cells to treat cutaneous wounds.

Genitourinary Tissue Engineering: Reconstruction and Research Models

Tissue engineering is an emerging field of research that initially aimed to produce 3D tissues to bypass the lack of adequate tissues for the repair or replacement of deficient organs. The basis of tissue engineering protocols is to create scaffolds, which can have a synthetic or natural origin, seeded or not with cells. At the same time, more and more studies have indicated the low clinic translation rate of research realised using standard cell culture conditions, i.e., cells on plastic surfaces or using animal models that are too different from humans. New models are needed to mimic the 3D organisation of tissue and the cells themselves and the interaction between cells and the extracellular matrix. In this regard, urology and gynaecology fields are of particular interest. The urethra and vagina can be sites suffering from many pathologies without currently adequate treatment options. Due to the specific organisation of the human urethral/bladder and vaginal epithelium, current research models remain poorly representative. In this review, the anatomy, the current pathologies, and the treatments will be described before focusing on producing tissues and research models using tissue engineering. An emphasis is made on the self-assembly approach, which allows tissue production without the need for biomaterials.

In Vitro Prevascularization of Self-Assembled Human Bone-Like Tissues and Preclinical Assessment Using a Rat Calvarial Bone Defect Model

In vitro prevascularization has the potential to address the challenge of maintaining cell viability at the core of engineered constructs, such as bone substitutes, and to improve the survival of tissue grafts by allowing quicker anastomosis to the host microvasculature. The self-assembly approach of tissue engineering allows the production of biomimetic bone-like tissue constructs including extracellular matrix and living human adipose-derived stromal/stem cells (hASCs) induced towards osteogenic differentiation. We hypothesized that the addition of endothelial cells could improve osteogenesis and biomineralization during the production of self-assembled human bone-like tissues using hASCs. Additionally, we postulated that these prevascularized constructs would consequently improve graft survival and bone repair of rat calvarial bone defects. This study shows that a dense capillary network spontaneously formed in vitro during tissue biofabrication after two weeks of maturation. Despite reductions in osteocalcin levels and hydroxyapatite formation in vitro in prevascularized bone-like tissues (35 days of culture), in vivo imaging of prevascularized constructs showed an improvement in cell survival without impeding bone healing after 12 weeks of implantation in a calvarial bone defect model (immunocompromised male rats), compared to their stromal counterparts. Globally, these findings establish our ability to engineer prevascularized bone-like tissues with improved functional properties.

Umbilical cord tissue cryopreservation: a short review

In this review we present current evidence on the possibility of umbilical cord tissue cryopreservation for subsequent clinical use. Protocols for obtaining umbilical cord-derived vessels, Wharton’s jelly-based grafts, multipotent stromal cells, and other biomedical products from cryopreserved umbilical cords are highlighted, and their prospective clinical applications are discussed. Examination of recent literature indicates we should expect high demand for cryopreservation of umbilical cord tissues in the near future.

Self-assembled human osseous cell sheets as living biopapers for the laser-assisted bioprinting of human endothelial cells

A major challenge during the engineering of voluminous bone tissues is to maintain cell viability in the central regions of the construct. In vitro prevascularization of bone substitutes relying on endothelial cell bioprinting has the potential to resolve this issue and to replicate the native bone microvasculature. Laser-assisted bioprinting (LAB) commonly uses biological layers of hydrogel, called 'biopapers', to support patterns of printed cells and constitute the basic units of the construct. The self-assembly approach of tissue engineering allows the production of biomimetic cell-derived bone extracellular matrix including living cells. We hypothesized that self-assembled osseous sheets can serve as living biopapers to support the LAB of human endothelial cells and thus guide tubule-like structure formation. Human umbilical vein endothelial cells were bioprinted on the surface of the biopapers following a predefined pattern of lines. The osseous biopapers showed relevant matrix mineralization and pro-angiogenic hallmarks. Our results revealed that formation of tubule-like structures was favored when the cellular orientation within the biopaper was parallel to the printed lines. Altogether, we validated that human osseous cell sheets can be used as biopapers for LAB, allowing the production of human prevascularized cell-based osseous constructs that can be relevant for autologous bone repair applications.

Quantitative analysis of composite umbilical cord tissue health using a standardized explant approach and an assay of metabolic activity

BACKGROUND

Umbilical cord (UC) tissue can be collected in a noninvasive procedure and is enriched in progenitor cells with potential therapeutic value. Mesenchymal stromal cells (MSCs) can be reliably harvested from fresh or cryopreserved UC tissue by explant outgrowth with no apparent impact on functionality. A number of stem cell banks offer cryopreservation of UC tissue, alongside cord blood, for future cell-based applications. In this setting, measuring and monitoring UC quality is critical.

MATERIALS AND METHODS

UC explants were evaluated using a plating and scoring system accounting for cell attachment and proliferation. Explant scores for fresh and cryopreserved-then-thawed tissue from the same UC were compared. Metabolic activity of composite UC tissue was also assayed after exposure of the tissue to conditions anticipated to affect UC quality and compared with explant scores within the same UC.

RESULTS

All fresh and cryopreserved tissues yielded MSC-like cells, and cryopreservation of the tissue did not prevent the ability to isolate MSCs by the explant method. Thawed UC tissue scores were 91% (±0.6%; P = 0.0009) that of the fresh, biologically identical tissue. Within the same UC, explant scores correlated well to both cell yield (R² = 0.85) and tissue metabolic activity (R² = 0.69).

DISCUSSION

A uniform explant scoring assay can provide information about the quality of composite UC tissue. Such quantitative measurement is useful for analysis of tissue variability and process monitoring. Additionally, a metabolic assay of UC tissue health provides results that correlate well to explant scoring results.

Choice of surrogate tissue influences neonatal EWAS findings

BACKGROUND

Epigenomes are tissue specific and thus the choice of surrogate tissue can play a critical role in interpreting neonatal epigenome-wide association studies (EWAS) and in their extrapolation to target tissue. To develop a better understanding of the link between tissue specificity and neonatal EWAS, and the contributions of genotype and prenatal factors, we compared genome-wide DNA methylation of cord tissue and cord blood, two of the most accessible surrogate tissues at birth.

METHODS

In 295 neonates, DNA methylation was profiled using Infinium HumanMethylation450 beadchip arrays. Sites of inter-individual variability in DNA methylation were mapped and compared across the two surrogate tissues at birth, i.e., cord tissue and cord blood. To ascertain the similarity to target tissues, DNA methylation profiles of surrogate tissues were compared to 25 primary tissues/cell types mapped under the Epigenome Roadmap project. Tissue-specific influences of genotype on the variable CpGs were also analyzed. Finally, to interrogate the impact of the in utero environment, EWAS on 45 prenatal factors were performed and compared across the surrogate tissues.

RESULTS

Neonatal EWAS results were tissue specific. In comparison to cord blood, cord tissue showed higher inter-individual variability in the epigenome, with a lower proportion of CpGs influenced by genotype. Both neonatal tissues were good surrogates for target tissues of mesodermal origin. They also showed distinct phenotypic associations, with effect sizes of the overlapping CpGs being in the same order of magnitude.

CONCLUSIONS

The inter-relationship between genetics, prenatal factors and epigenetics is tissue specific, and requires careful consideration in designing and interpreting future neonatal EWAS.

TRIAL REGISTRATION

This birth cohort is a prospective observational study, designed to study the developmental origins of health and disease, and was retrospectively registered on 1 July 2010 under the identifier NCT01174875 .

Simultaneous harvesting of endothelial progenitor cells and mesenchymal stem cells from the human umbilical cord

The human umbilical cord (UC) is usually discarded as biological waste. However, it has attracted interest as a source of cells including endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs), which have demonstrated enormous potential in regenerative medicine. The present study describes a convenient protocol that has been developed to sequentially extract these two cell types from a single UC. EPCs which had properties of progenitor cells were successfully isolated from the UC vein. These cells had cobble-shaped morphology and expressed Flt-1, KDR, VE-cadherin, von Willebrand factor and CD31 mRNA, in addition to CD73, CD105 and vascular endothelial growth factor receptor-2. In addition to absorbing fluorescent-labeled acetylated low density protein and binding to fluorescein isothiocyanate-UEA-l, they were able to form vascular tube-like structures on Matrigel. Typical fibroblast-like cells, which were isolated from the Wharton's jelly, were confirmed to be MSCs by their expression of CD73, CD90 and CD105, and their ability to differentiate into adipocytes and osteoblasts. Thus, the human UC-derived cells may be suitable for use in tissue engineering and cell therapy.

Concise Review: Wharton's Jelly: The Rich, but Enigmatic, Source of Mesenchymal Stromal Cells

The umbilical cord has become an increasingly used source of mesenchymal stromal cells for preclinical and, more recently, clinical studies. Despite the increased activity, several aspects of this cell population have been under‐appreciated. Key issues are that consensus on the anatomical structures within the cord is lacking, and potentially different populations are identified as arising from a single source. To help address these points, we propose a histologically based nomenclature for cord structures and provide an analysis of their developmental origins and composition. Methods of cell isolation from Wharton's jelly are discussed and the immunophenotypic and clonal characteristics of the cells are evaluated. The perivascular origin of the cells is also addressed. Finally, clinical trials with umbilical cord cells are briefly reviewed. Interpreting the outcomes of the many clinical studies that have been undertaken with mesenchymal stromal cells from different tissue sources has been challenging, for many reasons. It is, therefore, particularly important that as umbilical cord cells are increasingly deployed therapeutically, we strive to better understand the derivation and functional characteristics of the cells from this important tissue source. Stem Cells Translational Medicine2017;6:1620–1630

Developmental pathways to adiposity begin before birth and are influenced by genotype, prenatal environment and epigenome

BACKGROUND

Obesity is an escalating health problem worldwide, and hence the causes underlying its development are of primary importance to public health. There is growing evidence that suboptimal intrauterine environment can perturb the metabolic programing of the growing fetus, thereby increasing the risk of developing obesity in later life. However, the link between early exposures in the womb, genetic susceptibility, and perturbed epigenome on metabolic health is not well understood. In this study, we shed more light on this aspect by performing a comprehensive analysis on the effects of variation in prenatal environment, neonatal methylome, and genotype on birth weight and adiposity in early childhood.

METHODS

In a prospective mother-offspring cohort (N = 987), we interrogated the effects of 30 variables that influence the prenatal environment, umbilical cord DNA methylation, and genotype on offspring weight and adiposity, over the period from birth to 48 months. This is an interim analysis on an ongoing cohort study.

RESULTS

Eleven of 30 prenatal environments, including maternal adiposity, smoking, blood glucose and plasma unsaturated fatty acid levels, were associated with birth weight. Polygenic risk scores derived from genetic association studies on adult adiposity were also associated with birth weight and child adiposity, indicating an overlap between the genetic pathways influencing metabolic health in early and later life. Neonatal methylation markers from seven gene loci (ANK3, CDKN2B, CACNA1G, IGDCC4, P4HA3, ZNF423 and MIRLET7BHG) were significantly associated with birth weight, with a subset of these in genes previously implicated in metabolic pathways in humans and in animal models. Methylation levels at three of seven birth weight-linked loci showed significant association with prenatal environment, but none were affected by polygenic risk score. Six of these birth weight-linked loci continued to show a longitudinal association with offspring size and/or adiposity in early childhood.

CONCLUSIONS

This study provides further evidence that developmental pathways to adiposity begin before birth and are influenced by environmental, genetic and epigenetic factors. These pathways can have a lasting effect on offspring size, adiposity and future metabolic outcomes, and offer new opportunities for risk stratification and prevention of obesity.

CLINICAL TRIAL REGISTRATION

This birth cohort is a prospective observational study, designed to study the developmental origins of health and disease, and was retrospectively registered on 1 July 2010 under the identifier NCT01174875 .

Isolation and Culture of Single Cell Types from Rat Liver

There have been few reports on the simultaneous isolation of multiple liver cell populations thus far. As such, this study was aimed at establishing a protocol for the simultaneous separation of hepatocytes (HCs), hepatic stellate cells (HSCs), liver sinusoidal endothelial cells (LSECs) and Kupffer cells (KCs) from the rat liver and assessing the in vitro culture of these cells. Single-cell suspensions from the liver were obtained by ethylene glycol tetraacetic acid/collagenase perfusion. After low-speed centrifugal separation of HCs, pronase was added to the nonparenchymal cell fraction to eliminate the remaining HCs. Subsequently, HSCs, LSECs and KCs were purified by two steps of density gradient centrifugation using Nycodenz and Percoll in addition to selective attachment. Pronase treatment increased the HSC yield (1.5 ± 0.2 vs. 0.7 ± 0.3 cells/g liver, p < 0.05) and improved LSEC purity (93.6 ± 3.6 vs. 82.5 ± 5.6%, p < 0.01). The isolated cells could also be cultured in vitro. LSEC apoptosis began on day 3 and reached a maximum on day 7. A few surviving LSECs began proliferating and split to form a cobblestone, sheet-like appearance on day 14. The LSECs on day 14 lost fenestrations but retained scavenger function. Thus, viable and purified liver cells were obtained with a high yield from the rat liver using the developed method, which may be useful for studying the physiology and pathology of the liver in the future.

Stem cells: a promising source for vascular regenerative medicine

The rising and diversity of many human vascular diseases pose urgent needs for the development of novel therapeutics. Stem cell therapy represents a challenge in the medicine of the twenty-first century, an area where tissue engineering and regenerative medicine gather to provide promising treatments for a wide variety of diseases. Indeed, with their extensive regeneration potential and functional multilineage differentiation capacity, stem cells are now highlighted as promising cell sources for regenerative medicine. Their multilineage differentiation involves environmental factors such as biochemical, extracellular matrix coating, oxygen tension, and mechanical forces. In this review, we will focus on human stem cell sources and their applications in vascular regeneration. We will also discuss the different strategies used for their differentiation into both mature and functional smooth muscle and endothelial cells.

Potential of Newborn and Adult Stem Cells for the Production of Vascular Constructs Using the Living Tissue Sheet Approach

Bypass surgeries using native vessels rely on the availability of autologous veins and arteries. An alternative to those vessels could be tissue-engineered vascular constructs made by self-organized tissue sheets. This paper intends to evaluate the potential use of mesenchymal stem cells (MSCs) isolated from two different sources: (1) bone marrow-derived MSCs and (2) umbilical cord blood-derived MSCs. When cultured in vitro, a proportion of those cells differentiated into smooth muscle cell- (SMC-) like cells and expressed contraction associated proteins. Moreover, these cells assembled into manipulable tissue sheets when cultured in presence of ascorbic acid. Tubular vessels were then produced by rolling those tissue sheets on a mandrel. The architecture, contractility, and mechanical resistance of reconstructed vessels were compared with tissue-engineered media and adventitia produced from SMCs and dermal fibroblasts, respectively. Histology revealed a collagenous extracellular matrix and the contractile responses measured for these vessels were stronger than dermal fibroblasts derived constructs although weaker than SMCs-derived constructs. The burst pressure of bone marrow-derived vessels was higher than SMCs-derived ones. These results reinforce the versatility of the self-organization approach since they demonstrate that it is possible to recapitulate a contractile media layer from MSCs without the need of exogenous scaffolding material.

Umbilical Cord Tissue-Derived Cells as Therapeutic Agents

Although the characteristics of SC, including UC-derived cells, are a dramatically discussed issue, this review will focus particularly on some controversial issues regarding clinical utility of cells isolated from UC tissue. UC-derived cells have several advantages compared to other types and sources of stem cells. The impact of UC topography on cell characteristics is briefly discussed. The necessity to adapt existing methods of cell isolation and culturing to GMP conditions is mentioned, as well as possible cryopreservation of this material. Light is shed on some future perspectives for UC-derived cells.

Expression of epithelial markers by human umbilical cord stem cells. A topographical analysis

INTRODUCTION

Human umbilical cord stem cells have inherent differentiation capabilities and potential usefulness in regenerative medicine. However, the epithelial differentiation capability and the heterogeneity of these cells have not been fully explored to the date.

METHODS

We analyzed the expression of several undifferentiation and epithelial markers in cells located in situ in different zones of the umbilical cord -in situ analysis- and in primary ex vivo cell cultures of Wharton's jelly stem cells by microarray and immunofluorescence.

RESULTS

Our results demonstrated that umbilical cord cells were heterogeneous and had intrinsic capability to express in situ stem cell markers, CD90 and CD105 and the epithelial markers cytokeratins 3, 4, 7, 8, 12, 13, 19, desmoplakin and zonula occludens 1 as determined by microarray and immunofluorescence, and most of these markers remained expressed after transferring the cells from the in situ to the ex vivo cell culture conditions. However, important differences were detected among some cell types in the umbilical cord, with subvascular zone cells showing less expression of stem cell markers and cells in Wharton's jelly and the amnioblastic zones showing the highest expression of stem cells and epithelial markers.

CONCLUSIONS

These results suggest that umbilical cord mesenchymal cells have intrinsic potential to express relevant epithelial markers, and support the idea that they could be used as alternative cell sources for epithelial tissue engineering.

Improvement of cardiac function by placenta-derived mesenchymal stem cells does not require permanent engraftment and is independent of the insulin signaling pathway

INTRODUCTION

The objective of this work was to evaluate the efficacy of placenta-derived mesenchymal stem cell (MSC) therapy in a mouse model of myocardial infarction (MI). Since MSCs can be obtained from two different regions of the human term placenta (chorionic plate or villi), cells obtained from both these regions were compared so that the best candidate for cell therapy could be selected.

METHODS

For the in vitro studies, chorionic plate MSCs (cp-MSCs) and chorionic villi MSCs (cv-MSCs) were extensively characterized for their genetic stability, clonogenic and differentiation potential, gene expression, and immunophenotype. For the in vivo studies, C57Bl/6 mice were submitted to MI and, after 21 days, received weekly intramyocardial injections of cp-MSCs for 3 weeks. Cells were also stably transduced with a viral construct expressing luciferase, under the control of the murine stem cell virus (MSCV) promoter, and were used in a bioluminescence assay. The expression of genes associated with the insulin signaling pathway was analyzed in the cardiac tissue from cp-MSCs and placebo groups.

RESULTS

Morphology, differentiation, immunophenotype, and proliferation were quite similar between these cells. However, cp-MSCs had a greater clonogenic potential and higher expression of genes related to cell cycle progression and genome stability. Therefore, we considered that the chorionic plate was preferable to the chorionic villi for the isolation of MSCs. Sixty days after MI, cell-treated mice had a significant increase in ejection fraction and a reduction in end-systolic volume. This improvement was not caused by a reduction in infarct size. In addition, tracking of cp-MSCs transduced with luciferase revealed that cells remained in the heart for 4 days after the first injection but that the survival period was reduced after the second and third injections. Quantitative reverse transcription-polymerase chain reaction revealed similar expression of genes involved in the insulin signaling pathway when comparing cell-treated and placebo groups.

CONCLUSIONS

Improvement of cardiac function by cp-MSCs did not require permanent engraftment and was not mediated by the insulin signaling pathway.

Using human umbilical cord cells for tissue engineering: a comparison with skin cells

The epithelial cells and Wharton׳s jelly cells (WJC) from the human umbilical cord have yet to be extensively studied in respect to their capacity to generate tissue-engineered substitutes for clinical applications. Our reconstruction strategy, based on the self-assembly approach of tissue engineering, allows the production of various types of living human tissues such as skin and cornea from a wide range of cell types originating from post-natal tissue sources. Here we placed epithelial cells and WJC from the umbilical cord in the context of a reconstructed skin substitute in combination with skin keratinocytes and fibroblasts. We compared the ability of the epithelial cells from both sources to generate a stratified, differentiated skin-like epithelium upon exposure to air when cultured on the two stromal cell types. Conversely, the ability of the WJC to behave as dermal fibroblasts, producing extracellular matrix and supporting the formation of a differentiated epithelium for both types of epithelial cells, was also investigated. Of the four types of constructs produced, the combination of WJC and keratinocytes was the most similar to skin engineered from dermal fibroblasts and keratinocytes. When cultured on dermal fibroblasts, the cord epithelial cells were able to differentiate in vitro into a stratified multilayered epithelium expressing molecules characteristic of keratinocyte differentiation after exposure to air, and maintaining the expression of keratins K18 and K19, typical of the umbilical cord epithelium. WJC were able to support the growth and differentiation of keratinocytes, especially at the early stages of air-liquid culture. In contrast, cord epithelial cells cultured on WJC did not form a differentiated epidermis when exposed to air. These results support the premise that the tissue from which cells originate can largely affect the properties and homoeostasis of reconstructed substitutes featuring both epithelial and stromal compartments.