SKIN TOPOGRAPHY AS A MARKER FOR SKIN MATURATION

Abstract

The present invention relates to a method for determining the relief of the skin surface of a subject, and hence the degree of maturation of the said skin surface. Methods for identifying active agents, raw materials and formulation are also provided.

Claims

1.-14. (canceled)

15. A method, comprising: a) obtaining at least one sample (A) of skin cells of a child; b) contacting a candidate cosmetic product with the sample (A); c) obtaining an image of the sample (A) after step b) using methods of optical microscopy, scanning probe microscopy, electronic microscopy, optical tomography or optical profiling; d) measuring the developed surface of the skin of the sample (A); e) obtaining at least one control sample of skin wherein said sample has not been in contact with the candidate cosmetic product of step b); f) obtaining an image of the control sample of step e) using methods of optical microscopy, scanning probe microscopy, electronic microscopy, optical tomography or optical profiling; g) measuring the developed surface of the skin of said control sample; h) preparing a dermo-cosmetic composition for the skin of a child comprising the candidate cosmetic product of step b) when the developed surface measured in step d) is superior or equal to the developed surface measured in step g).

16. The method of claim 15, further comprising the step of determining the body surface area (BSA) of the child of step a).

17. The method claim 16, further comprising the steps of determining the ratio between the BSA of said child and the average BSA value in the adult population, and determining the corrected developed surface of the skin sample (A) of step a) by multiplying the developed skin surface of step d) by said ratio.

18. The method of claim 15, wherein said skin sample (A) is a replica of the skin surface of the child of step a).

19. The method of claim 15, wherein: said methods of optical microscopy are selected from the group consisting of conventional light microscopy, fluorescence microscopy, confocal/multiphoton microscopy and stimulated emission depletion; said methods of scanning probe microscopy are selected from the group consisting of scanning tunneling microscopy (STM), atomic force microscopy (AFM), near-field scanning optical microscopy; and said method of optical tomography is optical coherence tomography.

20. The method of claim 15, wherein the image of step c) and the measurement of the developed skin surface of step d) for said sample (A) is obtained by using optical profiling.

21. The method of claim 20, wherein optical profiling includes confocal microscopy and low coherence interferometry.

22. The method of claim 15, wherein the child of step a) is a newborn of 1 to 15 days, an infant of 5/6 weeks, an infant of 6 months±1 month, an infant of 1 year an infant of 4 to 5 years, 7 years or 10 years.

23. The method of claim 15, further comprising the step i) of administering an effective amount of the dermo-cosmetic composition of step h) to the skin of the child of step a).

24. A method, comprising: a) obtaining at least one sample (A′) of skin cells of a child affected by a skin disorder; b) obtaining an image of the sample (A′) of step a) using methods of optical microscopy, scanning probe microscopy, electronic microscopy, optical tomography or optical profiling; c) measuring the developed surface of the skin of said sample (A′); d) obtaining at least one control sample (B) of skin cells of a healthy child; e) obtaining an image of the sample (B) of step d) using methods of optical microscopy, scanning probe microscopy, electronic microscopy, optical tomography or optical profiling; f) measuring the developed surface of the skin of said sample (B); g) administering a composition or the formulation to the skin of the child of step a) for treating said skin disorder when the developed surface measured in step f) is superior or equal to the developed surface measured in step c).

25. The method of claim 24, further comprising the step of determining the body surface area (BSA) of the child of step a).

26. The method claim 25, further comprising the steps of determining the ratio between the BSA of said child and the average BSA value in the adult population, and determining the corrected developed surface of the skin sample (A′) of step a) by multiplying the developed skin surface of step c) by said ratio.

27. The method of claim 24, wherein said skin sample (A′) is a replica of the skin surface of the child of step a).

28. The method of claim 24, wherein: said methods of optical microscopy are selected from the group consisting of conventional light microscopy, fluorescence microscopy, confocal/multiphoton microscopy and stimulated emission depletion; said methods of scanning probe microscopy are selected from the group consisting of scanning tunneling microscopy (STM), atomic force microscopy (AFM), near-field scanning optical microscopy; and said method of optical tomography is optical coherence tomography.

29. The method of claim 24, wherein the image of step b) and the measurement of the developed skin surface of step c) for said sample (A′) is obtained by using optical profiling.

30. The method of claim 29, wherein optical profiling includes confocal microscopy and low coherence interferometry.

31. The method of claim 24, wherein the child of step a) is a newborn of 1 to 15 days, an infant of 5/6 weeks, an infant of 6 months±1 month, an infant of 1 year an infant of 4 to 5 years, 7 years or 10 years.

32. A method, comprising: a) obtaining at least one sample (A′) of skin cells of a child affected by a skin disorder; b) contacting a candidate active agent with the sample (A′) of step a); c) obtaining an image of the sample (A′) of step b) using methods of optical microscopy, scanning probe microscopy, electronic microscopy, optical tomography or optical profiling; d) measuring the developed surface of the skin of said sample (A′); e) obtaining at least one control sample of skin cells wherein said sample has not been in contact with the candidate active agent of step b); f) obtaining an image of the control sample of step e) using methods of optical microscopy, scanning probe microscopy, electronic microscopy, optical tomography or optical profiling; g) measuring the developed surface of the skin of said control sample; h) preparing a pharmaceutical formulation for children comprising the candidate active agent of step b) when the developed surface measured in step d) is superior or equal to the developed surface measured in step g).

33. The method of claim 32, further comprising the step of determining the body surface area (BSA) of the child of step a).

34. The method claim 33, further comprising the steps of determining the ratio between the BSA of said child and the average BSA value in the adult population, and determining the corrected developed surface of the skin sample (A′) of step a) by multiplying the developed skin surface of step d) by said ratio.

35. The method of claim 32, wherein said skin sample (A′) is a replica of the skin surface of the child of step a).

36. The method of claim 32, wherein: said methods of optical microscopy are selected from the group consisting of conventional light microscopy, fluorescence microscopy, confocal/multiphoton microscopy and stimulated emission depletion; said methods of scanning probe microscopy are selected from the group consisting of scanning tunneling microscopy (STM), atomic force microscopy (AFM), near-field scanning optical microscopy; and said method of optical tomography is optical coherence tomography.

37. The method of claim 32, wherein the image of step c) and the measurement of the developed skin surface of step d) for said sample (A′) is obtained by using optical profiling.

38. The method of claim 37, wherein optical profiling includes confocal microscopy and low coherence interferometry.

39. The method of claim 32, wherein the child of step a) is a newborn of 1 to 15 days, an infant of 5/6 weeks, an infant of 6 months±1 month, an infant of 1 year an infant of 4 to 5 years, 7 years or 10 years.

40. The method of claim 32, further comprising the step i) of administering an effective amount of the pharmaceutical formulation of step h) to the skin of the child of step a).

Description

FIGURE LEGENDS

[0125] FIG. 1: Developed surface.

[0126] FIG. 2: Evolution of the developed surface as a function of the age of the children.

[0127] FIG. 3: Evolution of the corrected developed surface as a function of the age of the children.

[0128] FIG. 4: A: Evolution of the corrected developed surface as a function of the age of the children (0-14 months); B: Evolution of the corrected developed surface as a function of the age of the children (12-60 months); C: Evolution of the corrected developed surface as a function of the age of the children (60-350 months). The points for each of the 3 identified maturation phases were used to draw a graph; the linear equation thereof was calculated using Excel.

EXPERIMENTAL EXAMPLE

[0129] In the study, replicas of the skin surface were collected on the volar forearm in 65 healthy male and female volunteers in 7 age groups (n=between 6 and 15 per group) [0130] group 1: 5-6 weeks (n=9), [0131] group 2: 6 months (±1 month; n=8), [0132] group 3: 1 year (n=7), [0133] group 4: 4-5 years (n=7), [0134] group 5: 7 years (n=13), [0135] group 6: 10 years (n=15) [0136] group 7 (adults): 20-35 years old (; n=6).

[0137] The replicas were analyzed by confocal microscopy, as previously described (Zahouani and Vargiolu, in “Measuring the Skin”, P. Agache & P. Humbert Eds, Springer, 2004).

[0138] A quantitative method of cutaneous relief imaging has been developed, wherein the topographical profile is considered as a distribution of heights spaced out at regular intervals (Zahouani and Vargiolu, in “Measuring the Skin”, P. Agache & P. Humbert Eds, Springer, 2004). The said method thus makes use of quantitative parameters which enable monitoring the changes of the skin surface relief. In addition, both micro- and macroreliefs can be analyzed with this method at the same time.

[0139] In particular, the said method enables the determination of the developed skin surface. The developed surface corresponds to the ratio between the area of the local elementary surfaces and the area of the measured zone (FIG. 1).

[0140] A first step according to this method is the identification of a reference plane of skin relief. Thus leveling the surface requires establishing the root mean square plane going through the experimental points. This method aims at minimizing the variations in relation to each of the coefficients of the average plane.

[0141] Then, the developed surface was calculated using the equation:

[00001]$S_{\mathrm{Dev}}=\frac{\underset{j=1}{\overset{N-1}{.Math.}}.Math.\underset{i=1}{\overset{M-1}{.Math.}}.Math.A_{\mathrm{ij}}}{\mathrm{Length}\times \mathrm{Width}}$

[0142] The resulting value showed a bell-shape distribution, with a peak at around 4-5 years (FIG. 2). This suggested a change in the maturation rate of the skin surface when children reached that age.

[0143] In order to confirm that this effect was not simply reflecting the general expansion of the skin surface, but was genuinely indicating an effect on the skin surface topography, the developed surface was linearized by a correction factor.

[0144] First, the body surface area in each age group was calculated according to the Mosteller formula (Mosteller, N Engl J Med, 317(17): 1098, 1987) using the mean height and weight of the said age group (Table 1):

BSA(m.sup.2)=([Height(cm)×Weight(kg)]/3600).sup.1/2

TABLE-US-00001 TABLE 1 Enrolled Age (months) Weight (kg) Height (cm) Group subjects Mean Mean Mean 1 9 1.425 4.7 55.2 2 8 5.9 7.7 67.1 3 7 12 10.3 77.1 4 7 56.4 20.5 111.4 5 13 84 24.7 127.8 6 15 120 41.6 146.8 7 6 321.6 70.4 174.3

[0145] All the BSA values were then normalized to the BSA of the adults, giving a correction factor which in turn used to correct the developed surface values (Table 2). The corrected developed surface values thus genuinely reflect changes in the topography of the skin surface.

TABLE-US-00002 TABLE 2 Corrected Developed Correction developed Age group surface BSA factor surface 5/6 weeks 130.7 0.27 0.15 19.05 6 months 126.6 0.38 0.21 26.01 1 years 130.8 0.47 0.25 33.28 4/5 years 134.1 0.80 0.43 58.84 7 years 128.8 0.94 0.51 65.35 10 years 127.3 1.29 0.70 89.36 adults 127.28 1.84 1.00 127.28

[0146] FIG. 3 shows the increase in the corrected developed surface area as a function of age.

[0147] Three rates of development can clearly be observed. The developed surface grows very fast until 1 year, reflecting a strong maturation of the skin (rate=1.35). In infants between 1 year and 4-5 years, the rate decreases but is still strong, indicating a second phase of maturation which is slower but more complex than the first one (rate=0.57). Finally, after 4-5 years, the growth of the developed surface slows down (rate=0.25), confirming the inflexion point seen on FIG. 4.

[0148] In conclusion, the inventors have shown that the major part of the maturation of the relief of the skin is complete by the time the children reach 4-5 years. In the following years, the maturation of the skin continues, albeit at a slower rate, which likely corresponds to a period of fine-tuning of the skin organization.