Functional melanocytes derived from human pluripotent stem cells engraft into pluristratified epidermis

Abstract

Melanocytes are essential for skin homeostasis and protection, and their defects in humans lead to a wide array of diseases that are potentially extremely severe. To date, the analysis of molecular mechanisms and the function of human melanocytes have been limited because of the difficulties in accessing large numbers of cells with the specific phenotypes. This issue can now be addressed via a differentiation protocol that allows melanocytes to be obtained from pluripotent stem cell lines, either induced or of embryonic origin, based on the use of moderate concentrations of a single cytokine, bone morphogenic protein 4. Human melanocytes derived from pluripotent stem cells exhibit all the characteristic features of their adult counterparts. This includes the enzymatic machinery required for the production and functional delivery of melanin to keratinocytes. Melanocytes also integrate appropriately into organotypic epidermis reconstructed in vitro. The availability of human cells committed to the melanocytic lineage in vitro will enable the investigation of those mechanisms that guide the developmental processes and will facilitate analysis of the molecular mechanisms responsible for genetic diseases. Access to an unlimited resource may also prove a vital tool for the treatment of hypopigmentation disorders when donors with matching haplotypes become available in clinically relevant banks of pluripotent stem cell lines.

In vitro modeling of hyperpigmentation associated to neurofibromatosis type 1 using melanocytes derived from human embryonic stem cells

“…Two hESC lines, NF1-1 and NF1-2, which carry a heterozygous deletion of four nucleotides leading to a stop codon in the NF1 gene, and two control cell lines were successfully differentiated toward homogenous populations of melanocytes as described previously (20). Melanocytes derived from NF1 and WT hESCs, termed mel-NF1 (mel-NF1-1 and mel-NF1-2) and mel-WT (mel-WT-1 and mel-WT-2), showed morphology typical of melanocytes associated with expression of tyrosinase-related protein 1 (TYRP1), a melanogenic enzyme (Fig.…”

“…This has changed recently with the emergence of differentiation protocols of human pluripotent stem cells into melanocytes (20,21). A growing number…”

Coloring skin with pluripotent stem cells

“…In 2011, we developed a direct differentiation protocol using a BMP4 treatment leading to formation of a pure and functional population of melanocytes from pluripotent stem cells. 11 In this study, we demonstrated that selected melanocytes derived from pluripotent stem cells, both of embryonic origin and following genetic reprogramming of adult cells, exhibit all the characteristic features of their adult counterparts. Finally, the functional status of melanocytes derived from pluripotent stem cells was assessed by demonstrating that these cells were capable of producing melanosomes, transferring melanin to neighboring keratinocytes in culture and integrating appropriately into the basal layer of organotypic epidermis reconstructed in vitro, extending their dendrites into the overlying layers.…”

Les cellules souches redonnent de la couleur à la peau

“…Citons MITF (microphthalmia-associated transcription factor), PAX3 (paired box 3), SOX10 (sex determining region Y-box 10), ou encore les cytokines citées plus haut et leurs récepteurs. Nous avons adapté le protocole mis en place pour obtenir des kératinocy-tes et étudié l'effet de modifications des concentrations de BMP4 : une forte concentration (5 à 0,5 nM) est requise pour obtenir les dérivés épidermiques, alors que les dérivés neuraux centraux qui permet de différencier des cellules souches pluripotentes, sans passage par l'étape de formation des corps embryoïdes, en une population pure et homogène de mélanocytes, capables de produire de la mélanine et de s'intégrer dans la couche basale d'un épiderme pluristratifié [5].…”