Objective To explore the possibility of bone marrow mesenchymal stem cells (MSCs) differentiating into active melanocytes in vitro.Methods Bone marrow stromal cells were harvested from femoral marrow of 6-week-old black male C57BL/6 mice,and subjected to a primary culture.After 6-passage subculture,an induction medium containing hydrocortisone,recombinant human insulin,transferrin and fibroblast growth factor was used to induce the differentiation of MSCs into melanocytes.Inverted light microscopy was applied to observe the process of cell differentiation,transmission electron microscopy to observe melanosome formation and maturation,and immunocytochemistry to determine the expression of melanocyte-associated epitopes,and flow cytometry to analyze cell cycles and yield of differentiated melanocytes.Results The total number of MSCs was close to 109 after 6 passages of subculture,and immunofluorescent studies showed an expression rate of 94.3％ for CD44 and 82.3％ for CD105 in these MSCs.After 180-day cultivation in the induction medium,the MSCs showed a morphological similarity to melanocytes with an increase in dendrites,formation of melanosome-like structures,and cell growth cycle was shortened to 3-4 days.Brown/black cell sediments were visualized by naked eyes.Electron microscopy revealed that intracellular melanosomes were mainly in Ⅳ phase.Immunofluorescence studies of the differentiated melanocytes showed a positive staining for tyrosinase related protein-1 (TRP-1),TRP-2,and microphthalmia-associated transcription factor (MITF).Flow cytometric analysis showed that most of the melanocytes differentiated from the MSCs were in G1 and S phases,and TRP-1-positive melanocytes amounted to 80％ of gate cells.Conclusions Bone marrow MSCs can be largely differentiated into melanocytes with a close similarity to normal melanocytes in morphology,ultrastructure and specific epitopes and a certain degree of proliferative activity.

Objective To study the correlation between vitamin D receptor(VDR)polymorphism and psoriasis in the Chinese patients.Methods VDR genotypes were determined by PCR-RFLP in 112unrelated psoriatic patients as well as 108unr elated healthy controls.Results AA and Bb genotypes were found to be ex-pressed more frequently in psoriatic patients(19.6%and 32.1%)than those in normal controls(7.4%and14.8%),respectively.However,no signifi cant correlation was identified between VDR polymorphismand sex,age at onset,family history of psoriasis in psoriatic patients.In addition,there was no significant difference in the fre-quency of A,a alleles and B,b alleles between normal controls and psoriatic patients.Conclusions There is a significant difference in VDR genotypes between psoriatic patients and normal controls.The presence of hom ozygote AA or heterozygote Bb might contribute to the susceptibility of psoriasis.

A 69-year-old man presented with a 3-year history of scattered erythematous patches, perifollicular papules, acneiform lesions(such as milia, cysts) on the head, trunk and limbs as well as alopecia and peripheral eosinophilia. Histopathological examination revealed chronic focal dermal and perifollicular inflammatory infiltration with vascular proliferation and presence of a small number of eosinophils. He was initially diagnosed with folliculitis, and treated with antihistamines and antibiotics. Thereafter, lesional inflammation and pruritus were attenuated. However, plaques and alopecia developed in the occipital area 3 months later. The second histopathology of biopsy specimens revealed a dense dermal infiltrate of lymphoid cells and eosinophils, perifollicular infiltrate with numerous lymphoid cells, eosinophils and atypical lymphocytes migrating into hair follicles. Alcian blue stain showed epidermal mucinosis in follicles. Immunohistochemical examination showed positive staining of atypical cells for CD3, CD4, CD5, CD2, CD43 and ubiquitin carboxyl-terminal esterase L1 (UCHL1), but negative staining for CD20, CD79a, Epstein-barr virus, CD56, phosphoglucomutase-1, myeloperoxidase, CD7, or AE1 and AE3 monoclonal anti-keratin antibodies. T-cell receptor gene rearrangement was undetected. He was diagnosed with folliculotropic mycosis fungoides. Novel skin lesions still emerged after treatment with photochemotherapy (PUVA) plus acitretin. Follow up of the patient still continued.