Why do Stretch Marks persist after Pregnancy ? (the answer is in the Elastic fibers)

Marked disruption and aberrant regulation of elastic fibres in early striae gravidarum.

Wang F, Calderone K, Smith NR, Do TT, Helfrich YR, Johnson TR, Kang S, Voorhees JJ, Fisher GJ.

• Br J Dermatol. 2015 Dec;173(6):1420-30. doi: 10.1111/bjd.14027. Epub 2015 Nov 8.

• Stretch marks  are the result of stretching of the skin in result of rapid skin volume changes for example during puberty and pregnancy. In the latter case, they are called Striae Gravidarum (SG)
• They are initially red (erythematous) but with time they become white, lax and have a scar-like appearance.
• Normally The capacity of the skin to regain its initial resting shape is dependent on elastic fibers composed of protein bundles called elastin but the study shows that in this condition of excessive prolonged stretching “useless” elastic fiber components are produced
• Normal Elastic fibers are synthesized by fibroblasts:
  • tropoelastin is the main component
  • fibrillins 1, 2 , 3 and 5 are also needed

In this US study from Johns Hopkins University published in the British Journal of Dermatology, 27 subjects were included:

• abdominal skin was removed from healthy pregnant women. Lesional (SG) and perilesional skin were analyzed
• control normal skin was removed from the hip
• in 8 subjects abdominal lesional and perilesional skin was removed 4-8 weeks after delivery

Skin sections were analyzed by immunostaining and gene expression was measured by RT-PCR (Polymerase Chain Reaction)

Results showed disruption of the elastic fibre network mainly in the middle to deep dermis:

• In place short, disorganized, thin, thread-like fibrils were seen. These fibrils were rich in tropoelastin. These fibrils remained after delivery (postpartum)
• This was accompanied by increased gene expression of tropoelastin and fibrillin 1 (but not 2, 3 and 5)

Conclusion

• Striae Gravidarum (SG) are the result of uncoordinated synthesis of elastic fibers (elastin) as the result of mechanical stretching:
• This translates into excessive synthesis of fibers called tropoelastin which persist.
• However, complete, functional elastic fibers are not produced as the other components are not synthesized (This is why the skin is lax)

Treatment wise, it is still another story…To read previous articles on stretch marks, click HERE. 

Comment: Hopefully this study adds the basis to understand the condition and this might lead to targeted effective therapy.

Article selection: Prof Dr Jean-Hilaire Saurat – dermatologist. Geneva, Switzerland