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REVIEW ARTICLE

Reconstructing hair follicle pigmentary unit using organoids and bioprinting

Qiaoli Xie1†* ,  Zhuojun Liu1† ,  Yijia Zhang1 ,  Meiling Ren1 ,  Bolin Chen1 ,  Fanrun Zeng1 ,  Xueli Han1 ,  Ruoqi Zhou1 ,  Chuqing Zhou1 ,  Xiao Xiang1 ,  Mingxing Lei1*
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1 Key Laboratory of Biorheological Science and Technology of Ministry of Education & 111 Project Laboratory of Biomechanics and Tissue Repair, College of Bioengineering, Chongqing University, Chongqing , China
†These authors contributed equally to this work.
IJB, 026300321 https://doi.org/10.36922/IJB026300321
Received: 25 July 2026 | Revised: 15 August 2026 | Accepted: 21 August 2026 | Published online: 21 August 2026
(This article belongs to the Special Issue 3D Bioprinting for Engineered Tissues and Organs)
© 2026 by the Author(s). This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 4.0 International License ( https://creativecommons.org/licenses/by/4.0/ )
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Abstract

Hair graying is a common feature of physiological aging and is typically evaluated by hair color, melanin content, or melanogenesis-related enzyme activity. However, growing evidence suggests that hair graying results from functional defects at multiple levels of the hair follicle pigmentary unit (HFPU). The HFPU comprises both the intrinsic melanocyte lineage and the extrinsic microenvironment that supports melanocyte function. Here, we review the application of emerging technologies, including organoids, biomaterials, bioprinting, and microphysiological systems, to HFPU reconstruction. Based on the biological functions directly demonstrated by different models, we define six ascending levels of evidence: pigment production, melanocyte differentiation, pigment transfer, progenitor cell maintenance, niche reconstruction, and durable or cycle-like regenerative capacity. Current three-dimensional models reproduce selected structural or cellular components of the HFPU, but remain limited in their ability to sustain melanocyte-lineage renewal, support coordinated pigment transfer, and restore pigmentary function after perturbation. Distinguishing transient hair darkening or short-term melanogenic activation from functional HFPU reconstruction gives a more rigorous evaluation of hair repigmentation models and the interventions tested using these models.

Graphical abstract
Keywords
Hair follicle pigmentary unit
Hair graying
Hair repigmentation
Melanocyte stem cells
Skin organoids
Bioprinting
Extracellular matrix
Mechanobiology
Funding
This work was supported by the National Key Research and Development Program of China (2023YFC2508200); the National Natural Science Foundation of China (82373509, 82574005); the Natural Science Foundation of Chongqing, China (CSTB2023NSCQ-MSX0463); and the Fundamental Research Funds for the Central Universities (2024CDJQYJCYJ-001).
Conflict of interest
The authors declare that there are no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
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International Journal of Bioprinting, Electronic ISSN: 2424-8002 Print ISSN: 2424-7723, Published by AccScience Publishing
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