Intermittent Cold Exposure and Brown Adipose Tissue Hyperplasia

NCT ID: NCT07048405

Last Updated: 2025-07-09

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

12 participants

Study Classification

INTERVENTIONAL

Study Start Date

2025-05-01

Study Completion Date

2026-07-31

Brief Summary

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This clinical trial explores how repeated short-term cold exposure impacts the molecular and physiological function of brown adipose tissue (BAT), a thermogenic organ associated with improved cardiometabolic health. While intermittent cold exposure has been shown to increase BAT activity and mass, as measured by fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography/computed tomography (PET/CT) scans, the molecular adaptations within BAT and other thermogenic tissues including skeletal muscle and white adipose tissue (WAT) remain poorly understood.

Healthy adults aged 18 to 40 years (6 males and 6 females) will participate in a 10-day cold acclimation protocol (2 hours per day using water-perfused cooling blankets). The primary objective is to determine how cold exposure alters cellular heterogeneity and gene expression in BAT, WAT, and skeletal muscle.

Participants will undergo baseline assessments, including measurements of energy expenditure, core and skin temperature, muscle activity, and blood sampling, each performed in both warm and cold conditions. These assessments will be followed by dynamic total-body PET/CT imaging during cold exposure and tissue biopsies from BAT, subcutaneous WAT, and skeletal muscle. These procedures will be repeated after the cold acclimation protocol to evaluate physiological and molecular changes. Additional outcomes include changes in energy expenditure, cold tolerance, and immune cell responses induced by cold exposure.

Detailed Description

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Twelve healthy adults aged 18-40 years old (6 female, 6 male) will:

* Attend baseline visits in both warm and cold conditions for blood sampling, measurement of energy expenditure, skin and core temperature, muscle activity. This will be followed by dynamic total-body 18F-FDG PET/CT scan during cold exposure.
* Undergo biopsies of BAT (supraclavicular), skeletal muscle (vastus lateralis), and subcutaneous WAT (periumbilical) under local anesthesia.
* Complete 10 consecutive days of cold acclimation (2 hours per day) using water-perfused cooling blankets.
* Return for follow-up assessments, including repeat blood sampling, energy expenditure, temperature measurements, PET/CT imaging, and tissue biopsies to evaluate post-acclimation changes.

Conditions

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Brown Adipose Tissue Cold Exposure 18F-FDG PET/CT

Study Design

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Allocation Method

NA

Intervention Model

SINGLE_GROUP

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

NONE

Study Groups

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Healthy normal weight subjects

Group Type EXPERIMENTAL

Cooling

Intervention Type OTHER

Participants will undergo cold exposure during the baseline and final visits (2.5 hours each visit), as well as throughout the 10-day cold acclimation period (2 hours per day). This will be achieved using water-perfused blankets set to individualized temperatures, selected to elicit comparable physiological responses across participants.

Biopsies

Intervention Type PROCEDURE

Under local anesthesia, biopsies will be obtained from the following sites:

* Brown adipose tissue from the supraclavicular (collarbone) region, guided by computed tomography (CT).
* White adipose tissue from the abdominal (periumbilical) area.
* Skeletal muscle from the outer thigh, specifically the vastus lateralis.

These biopsies will be performed both before and after the 10-day cold acclimation protocol.

Injection of 18F-FDG

Intervention Type RADIATION

Intravenous injection of 18F-FDG will be performed after 2 hours of cold exposure. This will be followed by a 30min dynamic total PET/CT scan while cold exposed using water-perfused blankets. These procedures will take place before and after the 10 day-cold acclimation protocol.

Indirect calorimetry

Intervention Type OTHER

Participants will rest quietly while oxygen consumption and carbon dioxide production are continuously recorded using a indirect calorimeter. These data will be used to calculate energy expenditure and respiratory exchange ratio. This procedure will take place before and after the 10 day-cold acclimation protocol.

Electromyogram

Intervention Type OTHER

Skin surface electrodes will be placed on major skeletal muscles to measure shivering and muscle activity during both warm and cold conditions. This procedure will take place before and after the 10 day-cold acclimation protocol.

Core and skin temperature monitoring

Intervention Type OTHER

Participants will ingest an electronic capsule that wirelessly and continuously monitors core body temperature. This procedure will be conducted before and after the 10-day cold acclimation protocol.

Additionally, wireless temperature sensors will placed at multiple standardized sites on the body to measure skin temperature. This procedure will be performed before, during, and after the 10-day cold acclimation protocol.

Interventions

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Cooling

Participants will undergo cold exposure during the baseline and final visits (2.5 hours each visit), as well as throughout the 10-day cold acclimation period (2 hours per day). This will be achieved using water-perfused blankets set to individualized temperatures, selected to elicit comparable physiological responses across participants.

Intervention Type OTHER

Biopsies

Under local anesthesia, biopsies will be obtained from the following sites:

* Brown adipose tissue from the supraclavicular (collarbone) region, guided by computed tomography (CT).
* White adipose tissue from the abdominal (periumbilical) area.
* Skeletal muscle from the outer thigh, specifically the vastus lateralis.

These biopsies will be performed both before and after the 10-day cold acclimation protocol.

Intervention Type PROCEDURE

Injection of 18F-FDG

Intravenous injection of 18F-FDG will be performed after 2 hours of cold exposure. This will be followed by a 30min dynamic total PET/CT scan while cold exposed using water-perfused blankets. These procedures will take place before and after the 10 day-cold acclimation protocol.

Intervention Type RADIATION

Indirect calorimetry

Participants will rest quietly while oxygen consumption and carbon dioxide production are continuously recorded using a indirect calorimeter. These data will be used to calculate energy expenditure and respiratory exchange ratio. This procedure will take place before and after the 10 day-cold acclimation protocol.

Intervention Type OTHER

Electromyogram

Skin surface electrodes will be placed on major skeletal muscles to measure shivering and muscle activity during both warm and cold conditions. This procedure will take place before and after the 10 day-cold acclimation protocol.

Intervention Type OTHER

Core and skin temperature monitoring

Participants will ingest an electronic capsule that wirelessly and continuously monitors core body temperature. This procedure will be conducted before and after the 10-day cold acclimation protocol.

Additionally, wireless temperature sensors will placed at multiple standardized sites on the body to measure skin temperature. This procedure will be performed before, during, and after the 10-day cold acclimation protocol.

Intervention Type OTHER

Other Intervention Names

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brown adipose tissue biopsy white adipose tissue biopsy skeletal muscle biopsy

Eligibility Criteria

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Inclusion Criteria

* Aged 18-40 years
* Body mass index 18.5-25 kg/m2
* Weight change of less than 5% in the past 6 months
* No acute or chronic medical conditions
* On no regular medications (other than contraceptives in female participants)
* No claustrophobia
* Alcohol intake ≤14 units/ week
* Screening blood tests within acceptable limits (of no clinical significance)
* Not currently pregnant, lactating or breastfeeding (female participants only)
* Ability to provide informed consent.

* Contra-indication to PET/CT scan
* Allergy to local anaesthetic
Minimum Eligible Age

18 Years

Maximum Eligible Age

40 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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University of Edinburgh

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Locations

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Royal Infirmary of Edinburgh

Edinburgh, , United Kingdom

Site Status RECRUITING

Countries

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United Kingdom

Central Contacts

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María Paula Huertas Caycedo

Role: CONTACT

01312429196

Facility Contacts

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María Paula Huertas Caycedo

Role: primary

01312429196

Other Identifiers

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24/SS/0094

Identifier Type: OTHER

Identifier Source: secondary_id

350117

Identifier Type: -

Identifier Source: org_study_id

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