The Role of Proteoglycans

 

During the past 45 years, extensive research has been carried out, focusing on the hair follicle and its unique functions and cycling. It has been clinically proven that proteoglycans, a specific type of protein, play a vital role in regulating the normal Hair Growth Cycle. 

 

The normal Hair Growth Cycle consists of three phases: the Growth phase (Anagen), the Transition phase (Catagen), and the Resting phase (Telogen).

1Growth Phase

Average duration: 3 years.

 

In the first phase of the normal Hair Growth Cycle, the Anagen (growth) phase, approximately 85-90% of the hair is actively growing at any given time.

 

Proteoglycans play an essential role in maintaining a balanced environment in the follicle that ensures the hair remains in the Anagen phase for the full duration and reduces the risk of premature shedding.

2Transition Phase

Average duration: 1-2 weeks.

 

While 85–90% of the follicles are in the Anagen (growth) phase, approximately 1% of the follicles are in the Catagen (transition) phase.

 

During the Catagen phase, the hair’s nutrient vessel – the dermal papilla – disconnects from the follicle, bringing the Anagen phase to an end. This transition from Anagen to Catagen is triggered by a natural decline in proteoglycan levels, leading to follicular regression.

3Resting Phase

Average duration: 3-4 months.

 

While the majority of hair follicles are in either the Anagen or Catagen phase, approximately 10–15% of follicles are in the Telogen (resting) phase at any given time.

 

During the Telogen phase, the hair, having reached its full growth potential, remains inactive within the follicle until it is shed. The follicle then generates a new hair, initiating a new Anagen phase and completing the normal Hair Growth Cycle. The transition from Catagen to Telogen is triggered when proteoglycan levels fall below a critical threshold. Their gradual recovery is essential for reactivating the Anagen phase.

It is clinically documented that several proteoglycans, including Versican, Syndecan, and Decorin, play a crucial role in maintaining the normal Hair Growth Cycle.

Proteoglycans Effect on the Hair Growth Signal

1Growth Phase

The Hair Growth Cycle is governed by a balance between growth-promoting Wnt proteins and their inhibitor, Dkk1. This balance determines not only whether hair grows, but also how long each phase of the hair growth cycle lasts.

 

Proteoglycans in the dermal papilla support Wnt signaling, helping to stabilise the follicle in the Anagen (growth) phase. As illustrated in the diagram, Anagen represents the longest portion of the hair cycle, during which active hair fiber production occurs.

2Transition Phase

When proteoglycan support is reduced, Dkk1 signaling becomes more dominant, triggering the transition into Catagen. Catagen is a short, transitional phase marked by follicle regression and shutdown of growth. In this phase, the hair strand detaches from the derma papilla.

3Resting Phase

Following Catagen, the follicle enters Telogen, a resting phase of intermediate length. During Telogen, no active growth occurs, and the hair is eventually shed, initiating reactivation of Wnt signaling, which allows the follicle to re-enter Anagen and begin a new growth cycle.

 

By sustaining Wnt activity and counteracting Dkk1, proteoglycans help prolong the Anagen phase, shorten time spent in regression, and maintain a healthy balance between Anagen, Catagen, and Telogen – this is known as the normal Hair Growth Cycle.

Proteoglycans Effect on the Hair Growth Signal

The Hair Growth Cycle is governed by a balance between growth-promoting Wnt proteins and their inhibitor, Dkk1. This balance determines not only whether hair grows, but also how long each phase of the hair growth cycle lasts.

 

Proteoglycans in the dermal papilla support Wnt signaling, helping to stabilise the follicle in the Anagen (growth) phase. As illustrated in the diagram, Anagen represents the longest portion of the hair cycle, during which active hair fiber production occurs.

 

When proteoglycan support is reduced, Dkk1 signaling becomes more dominant, triggering the transition into Catagen. Catagen is a short, transitional phase marked by follicle regression and shutdown of growth. In this phase, the hair strand detaches from the derma papilla. 

 

Following Catagen, the follicle enters Telogen, a resting phase of intermediate length. During Telogen, no active growth occurs, and the hair is eventually shed, initiating reactivation of Wnt signaling, which allows the follicle to re-enter Anagen and begin a new growth cycle.

 

By sustaining Wnt activity and counteracting Dkk1, proteoglycans help prolong the Anagen phase, shorten time spent in regression, and maintain a healthy balance between Anagen, Catagen, and Telogen – this is known as the normal Hair Growth Cycle.

Hair loss and hair growth disruptions can be explained by a ‘lower than normal’ concentration of hair growth regulating proteoglycans, which causes follicular degradation, known as Proteoglycan Follicular Atrophy.

 

 

Read more about Proteoglycan Replacement Therapy

Hair loss and hair growth disruptions can be explained by a ‘lower than normal’ concentration of hair growth regulating proteoglycans, which causes follicular degradation, known as Proteoglycan Follicular Atrophy (PFA).

 

 

Read more about PFA