**7. 2D vs. 3D cell cultures: advantages and disadvantages**

Monolayer 2D cell cultures do not always provide an accurate representation of *in vivo* processes [7]. The use of a single cell type [80], such as the use of keratinocytes only in skin cell cultures, [8] or the lack of interactions in 2D cell cultures of cell-to-cell or cell-to-extracellular matrix may be possible causes [5, 80]. However, advantages to using a 2D cell culture include ease of use, cost, and abundant scientific literature surrounding its use [81, 82].

created, onto which an epidermal layer was formed approximately 3 weeks later. Similarly, a 3D skin substitute using psoriatic skin cells was developed by Jean et al. [75] with either both psoriatic keratinocytes and fibroblasts or only one type of psoriatic cells (either keratinocytes or fibroblasts were psoriatic). Skin biopsies were obtained from patients with plaque psoriasis, and keratinocytes were extracted and seeded on to mouse fibroblasts and incubated at a temperature of 37°C [75]. For skin substitutes, ascorbic acid was used to culture the fibroblasts which formed dermal sheets that were altered to create a dermal layer onto which keratinocytes were then seeded to form an epidermal layer [75]. This method is the self-assembly method as the fibroblasts release their own extracellular matrix to maintain their growth [75]. A serum-free 3D psoriatic skin cell culture was similarly developed by Duque-Fernandez et al. [66]. This method is similar to the one presented by Jean et al. [75] and may be due to the fact that some authors are the same in both articles. The model by Duque-Fernandez et al. [76] was even used for testing percutaneous permeation of benzoic acid, caffeine, and hydrocortisone, using a Franz-diffusion cell method. This was compared to healthy skin substitutes and revealed that the psoriatic skin substitute had a greater permeability response to the three

For safety and efficacy testing of medications for psoriasis, commercially available 3D *in vitro* models also exist. Two examples of such models are the Psoriasis Skin Model by Creative Bioarray [77] and the model by MatTek Corporation [78]. According to Creative Bioarray [77], their skin model more closely mimics *in vivo* psoriatic skin vs. typical cell cultures as it allows for cell differentiation and can be used for testing of pharmaceutical products. The psoriasis model by MatTek Corporation can also be used for testing of dermatological products as it a 3D model composed of psoriatic fibroblasts while using normal human epidermal keratinocytes and is capable of mimicking *in vivo* psoriatic responses such as basal cell proliferation [78]. These examples were presented for a better understanding of the methods used in developing psoriatic human skin equivalents as well as the commercially available models for

testing the safety and efficacy of dermatological products used for psoriasis.

**6. 2D vs. 3D cell cultures: morphology and other characteristics**

breast cancer cells [79]. Drug efficacy may also differ in 2D and 3D cell cultures [79].

**7. 2D vs. 3D cell cultures: advantages and disadvantages**

Cell cultures that are 2D and 3D clearly differ with respect to their cell morphology as well as other characteristics. Cell cultures that grow in controlled flat environments, such as a Petri dish, are 2D cell cultures [6], and as such have cells that are flat in morphology [7]. Cell cultures that are 3D involve cells that are combined and shaped into a 3D spheroids using surrounding milieu or specialized conditions [7]. Cell viability also differs between 2D and 3D cell cultures. For example, 2D breast cancer cell cultures showed greater cell viability than 3D

Monolayer 2D cell cultures do not always provide an accurate representation of *in vivo* processes [7]. The use of a single cell type [80], such as the use of keratinocytes only in skin cell

compounds [76].

12 Cell Culture

3D cell cultures, on the other hand, provide a better imitation of *in vivo* processes as they allow for better understanding of the interactions that take place between cell-to-cell and cell-to-extracellular matrix [7]. Cell cultures that are 3D have also revealed to possess gene expression abilities, thus mimicking *in vivo* processes [83]. However, regardless of their improvements vs. the 2D cell cultures, typically 3D cell cultures still lack in their ability to provide key functions such as cellular waste removal [7]. Microfabricated cell cultures or on-chip cell cultures are advantageous in this instance as they provide microfluidic channels that enable the flow of nutrients and waste removal as well as the ability to mimic vasculature [51, 52]. Thus microfabricated 3D cell cultures are arguably the *in vitro* method of cell cultures that most closely mimic *in vivo* processes [50].

With respect to skin cell cultures, those that are 3D have the advantages of containing a stratum corneum and thus the ability of testing pharmaceutical products on the stratum corneum


**Table 1.** Summary of the advantages and disadvantages of 2D vs. 3D cell cultures.

as a skin barrier [40]. Other advantages to the use of 3D skin cell cultures include longer cell culture use between 10 and 30 days [40]. More recent human skin equivalent (HSE) cultures can even be used for up to 20 weeks [41]. Skin substitutes that are derived from only the epidermal layer and primarily keratinocytes are limited in their use for testing of products related to particular types of skin conditions that involve the immune system, including testing of products for wound healing [47]. Full thickness models consisting of both the epidermal and dermal layers are thus beneficial [8]. 3D bioprinting of skin constructs are also advantageous as they provide a greater accuracy in placement of cells and extracellular matrices as well as having the potential of imbedding vasculature in the skin construct as bioprinting of vasculature is also possible [54]. Skin constructs made through bioprinting are also considered to have high plasticity [54]. Skin bioprinting may also be used for developing 3D models for drug testing, such as diseased skin models, and are considered to provide more uniform models vs. manually developed skin models [55]. The primary disadvantage to the use of 3D skin cell cultures, however, is the cost associated with developing these cultures [40, 54]. See **Table 1** for a summary of the information presented in this section.

**Author details**

**References**

pp. 281-296

874-880

Press; 2006

Arezou Teimouri, Pollen Yeung and Remigius Agu\* \*Address all correspondence to: remigius.agu@dal.ca

[1] ThermoFisher Scientific. Introduction to Cell Culture. Available from: https://www. thermofisher.com/ca/en/home/references/gibco-cell-culture-basics/introduction-to-cell-

2D vs. 3D Cell Culture Models for *In Vitro* Topical (Dermatological) Medication Testing

http://dx.doi.org/10.5772/intechopen.79868

15

[2] Carter M, Shieh JC. Chapter 13—Cell culture techniques. In: Carter M, Shieh JC, editors. Guide to Research Techniques in Neuroscience. New York: Academic Press; 2010.

[3] Philippeos C, Hughes RD, Dhawan A, Mitry RR. Introduction to cell culture. Methods in

[4] MicroscopeMaster. Cell Culture—Basics, Techniques and Media. Available from: https://

[5] Coulomb B, Dubertret L. Skin cell culture and wound healing. Wound Repair and Regene-

[6] Duval K, Grover H, Han LH, Mou Y, Pegoraro AF, Fredberg J, et al. Modeling physiological events in 2D vs. 3D cell culture. Physiology (Bethesda). 2017;**32**(4):266-277 [7] Edmondson R, Broglie J, Adcock A, Yang L. Three-dimensional cell culture systems and their applications in drug discovery and cell-based biosensors. Assay and Drug

[8] MacNeil S. Progress and opportunities for tissue-engineered skin. Nature. 2007;**445**(7130):

[9] Rheinwald JG, Green H. Epidermal growth factor and the multiplication of cultured

[10] Nicholas MN, Jeschke MG, Amini-Nik S. Methodologies in creating skin substitutes.

[11] Breslin S, O'Driscoll L. Three-dimensional cell culture: The missing link in drug discovery.

[12] Davis J. Animal Cell Culture: Essential Methods. Chichester, West Sussex: Wiley; 2011

[13] Celis JE. Cell Biology, Four-Volume Set: A Laboratory Handbook. Amsterdam: Academic

www.microscopemaster.com/cell-culture.html [Accessed: 25-04-2018]

Dalhousie University, Halifax, Canada

culture.html [Accessed: 25-04-2018]

Molecular Biology. 2012;**806**:1

ration. 2002;**10**(2):109-112

Development Technologies. 2014;**12**(4):207-218

Drug Discovery Today. 2013;**18**(5):240-249

human epidermal keratinocytes. Nature. 1977;**265**(5593):421

Cellular and Molecular Life Sciences. 2016;**73**(18):3453-3472
