# Gluthanol™: cartilage glutathione

> Cartilage glutathione is the glutathione made and held inside chondrocytes, the cells of joint cartilage. Gluthanol™ is a proprietary blend of N-acetylcysteine, L-glycine, L-glutamine and alpha-lipoic acid built to supply the raw materials chondrocytes make glutathione from. It is the Nourish technology in a 3-in-1 joint system with MMP13 Cartilage Technology™ (Soothe, https://mmp13.com). Every fact on the site is cited to a PubMed-indexed paper, labelled by evidence type. Gluthanol™ was developed in New Zealand by researchers at Koru Nutrition. The Gluthanol blend itself has not yet been tested in a published study.

## Key facts
- Glutathione is a tripeptide of glutamate, cysteine and glycine, and the most abundant small thiol that cells make. (PMID 18796312)
- Articular cartilage has no blood vessels, lymphatics or nerves; chondrocytes make up about 2% of its volume. (PMID 23015907)
- Cartilage holds more glutathione than the meniscus or infrapatellar fat pad, but it is more prone to age-related oxidation. (PMID 31522568)
- More than twice as many chondrocytes from donors aged 50 and over died under oxidant stress as cells from donors aged 18 to 49. (PMID 14673993)
- Removing cystine from the culture medium depleted chondrocyte glutathione and made the cells more vulnerable. (PMID 14673993)
- Cysteine supply and glutamate cysteine ligase are the two key controls on glutathione synthesis. (PMID 22995213)
- Compressive loading oxidises cartilage glutathione; unloaded periods are needed for it to recover. (PMID 31522568)
- Hydrogen peroxide lowered SOX9 and raised MMP13 in cells from healthy human cartilage. (PMID 30403881)
- In older adults, supplying cysteine and glycine raised red-cell glutathione by about 95% in two weeks. (PMID 21795440)

## Core pages
- [Cartilage glutathione](https://gluthanol.com/cartilage-glutathione): Cartilage glutathione is the antioxidant chondrocytes make from glutamate, cysteine and glycine. How it is made, what uses it up, what changes after 50.
- [Gluthanol](https://gluthanol.com/technology): Gluthanol™ is a blend of NAC, glycine, glutamine and alpha-lipoic acid built to supply the raw materials cartilage cells make glutathione from.
- [Ingredients](https://gluthanol.com/ingredients): The four parts of Gluthanol™, their place in glutathione synthesis and what the cartilage research found, with the model it was found in.
- [Study library](https://gluthanol.com/studies): 27 peer-reviewed studies on cartilage glutathione and the ingredients that supply it, labelled by evidence type and linked to PubMed.
- [Questions](https://gluthanol.com/questions): Plain answers to common questions about cartilage glutathione, NAC, glycine, GlyNAC and oral glutathione, each cited to research on PubMed.
- [Glossary](https://gluthanol.com/glossary): Plain-English definitions of the terms used in cartilage glutathione research, from chondrocyte and GSH:GSSG to GPX4 and GlyNAC.
- [About](https://gluthanol.com/about): Why this site exists, how we choose and label research, and what it can and can't tell you.

## Questions
- [What is cartilage glutathione?](https://gluthanol.com/what-is-cartilage-glutathione): Cartilage glutathione is the glutathione made and held inside chondrocytes, the cells that build and maintain joint cartilage. Glutathione is a small antioxidant the cells make for themselves from three amino acids, glutamate, cysteine and glycine. Cartilage holds more of it than the meniscus or the knee's fat pad, and it is more prone to age-related oxidation ((Zhu 2020)).
- [How do cartilage cells make glutathione?](https://gluthanol.com/how-do-cartilage-cells-make-glutathione): Cartilage cells make glutathione in two enzyme steps. Glutamate cysteine ligase joins glutamate to cysteine, then glutathione synthetase adds glycine. How much a cell can make depends mainly on its cysteine supply and on that first enzyme ((Lu 2013)). Once used, glutathione is turned back into its working form by glutathione reductase ((Del Carlo 2003)).
- [What happens to cartilage glutathione with age?](https://gluthanol.com/what-happens-to-cartilage-glutathione-with-age): With age, cartilage cells tend to hold more of their glutathione in its used, oxidised form and cope worse with oxidative stress. In human cartilage cells, more than twice as many cells from donors aged 50 and over died under oxidant stress as cells from donors aged 18 to 49 ((Del Carlo 2003)), and in rats cartilage glutathione was more susceptible to age-related oxidation than other joint tissues ((Zhu 2020)).
- [What does oxidative stress do to cartilage?](https://gluthanol.com/oxidative-stress-and-cartilage): Oxidative stress is when a cell makes more reactive oxygen species than its antioxidants can clear. In cartilage it disrupts the cells' signalling and contributes to cartilage breakdown and cell death ((Bolduc 2019)). In cells from healthy human cartilage, hydrogen peroxide lowered SOX9, the cells' identity switch, and raised MMP13, the enzyme that cuts cartilage collagen ((Rong 2019)).
- [What is the GSH:GSSG ratio, and why does it matter for cartilage?](https://gluthanol.com/gsh-gssg-ratio): GSH is glutathione in its working, reduced form; GSSG is the used, oxidised form, two molecules joined. The GSH:GSSG ratio is a standard read-out of a cell's redox state: the higher it is, the more antioxidant capacity is in reserve. Cartilage cells from older donors had a higher ratio of GSSG to GSH and were more likely to die under oxidant stress ((Del Carlo 2003)).
- [Does loading a joint use up cartilage glutathione?](https://gluthanol.com/does-loading-use-up-cartilage-glutathione): In the short term, yes. In cow cartilage, cyclic compressive loading oxidised glutathione, and unloaded periods were needed for it to recover and for the tissue's total antioxidant capacity to rise ((Zhu 2020)). Movement is also how cartilage is fed: the flow of water through loaded cartilage carries nutrients to its cells ((Sophia Fox 2009)).
- [Cartilage has no blood supply. How are its cells fed?](https://gluthanol.com/why-cartilage-has-no-blood-supply): Articular cartilage has no blood vessels, lymphatics or nerves. Its cells, which make up about 2% of its volume, are fed by the movement of water through the tissue as it is compressed and released, which carries nutrients to them ((Sophia Fox 2009)). Living without a blood supply also means the cells must make their own protection, including glutathione ((Stegen 2020)).
- [Can you raise glutathione by taking it by mouth?](https://gluthanol.com/can-you-take-glutathione-by-mouth): The evidence is mixed. A single 3 g dose of oral glutathione did not raise plasma glutathione in healthy volunteers, because it was broken down in the gut and liver ((Witschi 1992)). But daily doses of 250 or 1,000 mg for six months did raise glutathione stores in blood cells, plasma and cheek cells ((Richie 2015)). None of these studies measured cartilage.
- [Glutathione or its building blocks: which raises glutathione?](https://gluthanol.com/glutathione-precursors-vs-glutathione): Both routes have raised glutathione in people, measured in blood. Taking glutathione daily for months raised blood levels ((Richie 2015)), and supplying its building blocks, cysteine and glycine, raised red-cell glutathione in older adults ((Sekhar 2011); (Kumar 2023)). The building-block route works with the cell's own machinery. None of the studies in our library compared the two head to head.
- [What is GlyNAC?](https://gluthanol.com/what-is-glynac): GlyNAC is a combination of glycine and N-acetylcysteine (NAC), two of glutathione's building blocks, studied as a way to correct glutathione deficiency in older adults. In a 16-week placebo-controlled trial in 24 older adults it corrected glutathione deficiency and improved oxidative stress, inflammation, gait speed and strength ((Kumar 2023)). A larger two-week trial found a benefit only in people with high oxidative stress and low glutathione ((Lizzo 2022)).
- [What does N-acetylcysteine (NAC) do in cartilage?](https://gluthanol.com/nac-and-cartilage): N-acetylcysteine (NAC) is a stable source of cysteine, the building block whose supply most limits how much glutathione a cell can make ((Lu 2013)). In cartilage cells NAC prevented nitric oxide-induced death through glutathione ((Nakagawa 2010)), and given by mouth to rats it held back MMP13, type II collagen loss and osteoarthritis development ((Kaneko 2019)).
- [Why does glycine matter for cartilage?](https://gluthanol.com/glycine-and-cartilage): Glycine is one of the three building blocks of glutathione, and it is also the most common amino acid in collagen, making up about one in every three. In cow cartilage cells, raising glycine increased type II collagen production by 60 to 75% ((de Paz-Lugo 2018)), and one analysis estimates the body's glycine supply may fall about 10 g a day short of its needs ((Meléndez-Hevia 2009)).
- [What does glutamine do for cartilage cells?](https://gluthanol.com/glutamine-and-cartilage-cells): Glutamine is the cell's main source of glutamate, the first building block of glutathione. In growth-plate cartilage, the identity switch SOX9 raised glutamine use, and glutathione made from glutamine kept reactive oxygen species down so the cells could survive without a blood supply ((Stegen 2020)). In rabbit cartilage cells, glutamine protected against heat stress and nitric oxide ((Tonomura 2006)).
- [What does alpha-lipoic acid do for cartilage glutathione?](https://gluthanol.com/alpha-lipoic-acid-and-cartilage): Alpha-lipoic acid, once reduced inside cells to dihydrolipoic acid, raises cellular glutathione by helping cells take up cysteine, mainly in cells that are short of it ((Han 1997)). In rats it lessened cartilage damage and oxidative markers ((Wang 2016)), and in mouse cartilage cells it protected glutathione and GPX4 and suppressed ferroptosis ((Chen 2026)).
- [How are cartilage glutathione and MMP13 connected?](https://gluthanol.com/glutathione-and-mmp13): Oxidative stress is one of the signals that switches on MMP13, the enzyme that cuts cartilage collagen. In cells from healthy human cartilage, hydrogen peroxide raised MMP13 and lowered SOX9 ((Rong 2019)). Supporting the cell's glutathione had the opposite effect in animal studies: oral NAC held back MMP13 in rats ((Kaneko 2019)), and dihydrolipoic acid held it back in mice ((Chen 2026)).
- [What is ferroptosis, and what does it have to do with cartilage glutathione?](https://gluthanol.com/ferroptosis-and-cartilage): Ferroptosis is an iron-dependent form of cell death driven by damage to cell membranes. GPX4, an enzyme that needs glutathione to work, is the cell's main brake on it. GPX4 was lower in damaged cartilage from osteoarthritis patients than in undamaged cartilage, and lowering it worsened osteoarthritis in an animal model ((Miao 2022)).
- [What is Gluthanol™?](https://gluthanol.com/what-is-gluthanol): Gluthanol™ is a proprietary blend of N-acetylcysteine, L-glycine, L-glutamine and alpha-lipoic acid, built to supply the raw materials cartilage cells make glutathione from. Three parts are glutathione's building blocks: cysteine (from NAC), glycine, and glutamate (from glutamine). The fourth, alpha-lipoic acid, helps cells take up cysteine ((Han 1997)). It is the Nourish technology in a 3-in-1 joint system.

## Study summaries
- [Cartilage cells from donors over 50 died more readily under oxidant stress](https://gluthanol.com/study-del-carlo-2003-older-cartilage-cells-glutathione): PMID 14673993
- [Cartilage holds more glutathione than nearby joint tissues, and loading oxidises it](https://gluthanol.com/study-zhu-2020-cartilage-glutathione-loading-ageing): PMID 31522568
- [Review: with age, cartilage cells make more oxidants than their defences can handle](https://gluthanol.com/study-bolduc-2019-oxidants-ageing-cartilage-review): PMID 30176344
- [In older cartilage cells, oxidised antioxidant enzymes switch survival signals off](https://gluthanol.com/study-collins-2016-peroxiredoxin-oxidation-older-cartilage-cells): PMID 26797130
- [The antioxidant master switch Nrf2 is lower in older and osteoarthritic cartilage cells](https://gluthanol.com/study-taylor-2023-nrf2-lower-in-older-cartilage-cells): PMID 37160250
- [Glutathione enzyme GPX4 is lower in damaged cartilage, and losing it worsens osteoarthritis](https://gluthanol.com/study-miao-2022-gpx4-ferroptosis-osteoarthritis): PMID 35101656
- [Hydrogen peroxide pushed human cartilage cells towards an osteoarthritis-like state](https://gluthanol.com/study-rong-2019-oxidative-stress-sox9-mmp13): PMID 30403881
- [Review: cartilage has no blood vessels, and its cells are only about 2% of its volume](https://gluthanol.com/study-sophia-fox-2009-basic-science-of-cartilage): PMID 23015907
- [Review: cysteine supply and one key enzyme control how fast cells make glutathione](https://gluthanol.com/study-lu-2013-how-glutathione-is-made): PMID 22995213
- [Review: glutathione, the most abundant small thiol cells make, and how it protects them](https://gluthanol.com/study-forman-2009-glutathione-overview): PMID 18796312
- [Older adults made glutathione more slowly; two weeks of cysteine and glycine restored it](https://gluthanol.com/study-sekhar-2011-older-adults-glutathione-cysteine-glycine): PMID 21795440
- [GlyNAC pilot: 24 weeks raised glutathione in older adults, and gains faded after stopping](https://gluthanol.com/study-kumar-2021-glynac-pilot-older-adults): PMID 33783984
- [In a placebo-controlled trial, 16 weeks of GlyNAC corrected low glutathione in older adults](https://gluthanol.com/study-kumar-2023-glynac-randomised-trial-older-adults): PMID 35975308
- [Two weeks of GlyNAC did not raise glutathione in healthy older adults overall](https://gluthanol.com/study-lizzo-2022-glynac-trial-healthy-older-adults): PMID 35821844
- [A single 3 g dose of glutathione by mouth did not raise blood plasma glutathione](https://gluthanol.com/study-witschi-1992-oral-glutathione-single-dose): PMID 1362956
- [Six months of daily oral glutathione raised glutathione stores in healthy adults](https://gluthanol.com/study-richie-2015-oral-glutathione-six-month-trial): PMID 24791752
- [One-month pilot: liposomal glutathione by mouth raised blood glutathione in 12 adults](https://gluthanol.com/study-sinha-2018-liposomal-glutathione-pilot): PMID 28853742
- [NAC protected cartilage cells through glutathione and limited damage in rat knees](https://gluthanol.com/study-nakagawa-2010-nac-protects-cartilage-cells-via-glutathione): PMID 19725096
- [NAC by mouth slowed osteoarthritis in rats and held back the enzyme MMP13](https://gluthanol.com/study-kaneko-2019-oral-nac-osteoarthritis-rats): PMID 31822750
- [NAC in cartilage-targeted nanoparticles restored glutathione and protected mouse cartilage](https://gluthanol.com/study-wang-2026-nac-nanoparticles-cartilage-gpx4): PMID 41537173
- [Extra glycine raised type II collagen production by cartilage cells by 60 to 75%](https://gluthanol.com/study-de-paz-lugo-2018-glycine-type-ii-collagen): PMID 30006659
- [Analysis: the body may fall about 10 g a day short of the glycine it needs](https://gluthanol.com/study-melendez-hevia-2009-glycine-shortfall): PMID 20093739
- [Growing cartilage cells use glutamine to make glutathione and survive without blood vessels](https://gluthanol.com/study-stegen-2020-glutamine-cartilage-cells-glutathione): PMID 32470321
- [Glutamine almost fully prevented cartilage cell death under heat and nitric oxide](https://gluthanol.com/study-tonomura-2006-glutamine-protects-cartilage-cells): PMID 16480901
- [Lipoic acid helped cells make their own glutathione by easing cysteine uptake](https://gluthanol.com/study-han-1997-lipoic-acid-raises-cell-glutathione): PMID 9288403
- [Alpha-lipoic acid lessened cartilage damage in rats with induced osteoarthritis](https://gluthanol.com/study-wang-2016-alpha-lipoic-acid-rat-cartilage): PMID 27055478
- [Active form of lipoic acid protected cartilage cell glutathione and slowed damage in mice](https://gluthanol.com/study-chen-2026-dihydrolipoic-acid-ferroptosis-cartilage): PMID 41539373

## Glossary
- [Aggrecan](https://gluthanol.com/glossary-aggrecan): Aggrecan is the large proteoglycan of cartilage, a protein core carrying many sugar chains that draw in water and let cartilage resist compression. It sits within the type II collagen network.
- [Alpha-lipoic acid](https://gluthanol.com/glossary-alpha-lipoic-acid): Alpha-lipoic acid is a small sulphur-containing fatty acid that the body makes in small amounts and uses as a helper for energy-producing enzymes in mitochondria. Inside cells it is reduced to dihydrolipoic acid, its antioxidant form.
- [Antioxidant](https://gluthanol.com/glossary-antioxidant): An antioxidant is a molecule that neutralises reactive oxygen species or limits the damage they cause, usually by giving up electrons. Some come from food; others, such as glutathione, cells make for themselves.
- [Articular cartilage](https://gluthanol.com/glossary-articular-cartilage): Articular cartilage is the smooth, slippery tissue that covers the ends of bones in moving joints, letting them glide and spreading load with low friction. It has no blood vessels, lymphatics or nerves.
- [Avascular](https://gluthanol.com/glossary-avascular): Avascular means without blood vessels. Adult articular cartilage is avascular, so its cells get oxygen and nutrients by diffusion through the tissue rather than from a blood supply.
- [Chondrocyte](https://gluthanol.com/glossary-chondrocyte): A chondrocyte is the resident cell of cartilage, the cell that makes and maintains the surrounding tissue. In articular cartilage, chondrocytes make up only about 2% of the volume.
- [Cysteine](https://gluthanol.com/glossary-cysteine): Cysteine is a sulphur-containing amino acid and the building block that gives glutathione its working thiol group. Its supply is one of the two key controls on how fast cells make glutathione.
- [Cystine](https://gluthanol.com/glossary-cystine): Cystine is two cysteine molecules joined by a disulphide bond, the form in which much of the cysteine outside cells is found. Cells take it in and split it back into cysteine to make glutathione.
- [Dihydrolipoic acid](https://gluthanol.com/glossary-dihydrolipoic-acid): Dihydrolipoic acid (DHLA) is the reduced, active form of alpha-lipoic acid, with two free thiol groups that can give up electrons. Cells make it from alpha-lipoic acid.
- [Ferroptosis](https://gluthanol.com/glossary-ferroptosis): Ferroptosis is a form of programmed cell death driven by iron and the oxidation of fats in cell membranes (lipid peroxidation). It is held back by glutathione and the glutathione-dependent enzyme GPX4.
- [Glutamate](https://gluthanol.com/glossary-glutamate): Glutamate is an amino acid and one of glutathione's three building blocks, joined to cysteine in the first step of glutathione synthesis. Cells get it from food, from other amino acids and from glutamine.
- [Glutamate cysteine ligase](https://gluthanol.com/glossary-glutamate-cysteine-ligase): Glutamate cysteine ligase (GCL) is the enzyme that carries out the first and rate-limiting step of glutathione synthesis, joining glutamate to cysteine. Its activity and the supply of cysteine are the two key controls on how much glutathione a cell makes.
- [Glutamine](https://gluthanol.com/glossary-glutamine): Glutamine is the most abundant amino acid in the blood and a ready source of glutamate, one of glutathione's three building blocks. Cells convert it to glutamate with the enzyme glutaminase.
- [Glutathione](https://gluthanol.com/glossary-glutathione): Glutathione is a tripeptide, a small molecule built from three amino acids (glutamate, cysteine and glycine), that cells make for themselves to defend against oxidative stress. It is the most abundant non-protein thiol in mammalian tissues.
- [Glutathione precursor](https://gluthanol.com/glossary-glutathione-precursor): A glutathione precursor is a nutrient that cells use to make glutathione themselves, such as cysteine (often given as NAC), glycine, or glutamine as a source of glutamate. Precursors support the cell's own production rather than supplying finished glutathione.
- [Glutathione reductase](https://gluthanol.com/glossary-glutathione-reductase): Glutathione reductase is the enzyme that recycles oxidised glutathione (GSSG) back into two molecules of working, reduced glutathione (GSH), using electrons from NADPH.
- [Glutathione synthetase](https://gluthanol.com/glossary-glutathione-synthetase): Glutathione synthetase is the enzyme that carries out the second and final step of glutathione synthesis, adding glycine to gamma-glutamylcysteine to make finished glutathione.
- [Gluthanol](https://gluthanol.com/glossary-gluthanol): Gluthanol™ is a proprietary blend of N-acetylcysteine, L-glycine, L-glutamine and alpha-lipoic acid. Three of the four supply the building blocks cartilage cells make glutathione from, and alpha-lipoic acid helps cells use cysteine and recycle antioxidants.
- [Glycine](https://gluthanol.com/glossary-glycine): Glycine is the smallest amino acid and one of glutathione's three building blocks. It also makes up a third of the amino acids in collagen, so cartilage cells need it for both their antioxidant and their matrix.
- [GlyNAC](https://gluthanol.com/glossary-glynac): GlyNAC is the combination of glycine and N-acetylcysteine (NAC), two glutathione precursors given together so cells have both glycine and cysteine for making glutathione.
- [GPX4](https://gluthanol.com/glossary-gpx4): GPX4 (glutathione peroxidase 4) is an enzyme that uses glutathione to disarm oxidised fats in cell membranes. It is the cell's main brake on ferroptosis, a form of cell death driven by fat oxidation.
- [GSH:GSSG ratio](https://gluthanol.com/glossary-gsh-gssg-ratio): The GSH:GSSG ratio compares the amount of working, reduced glutathione (GSH) with the amount of used, oxidised glutathione (GSSG) in a cell or fluid. A lower ratio means more of the glutathione pool is oxidised, a common sign of oxidative stress.
- [Lipid peroxidation](https://gluthanol.com/glossary-lipid-peroxidation): Lipid peroxidation is the oxidative damage of fats, especially the polyunsaturated fats in cell membranes, by reactive oxygen species. Its runaway form drives ferroptosis, and its by-products are used as markers of oxidative stress.
- [MMP13](https://gluthanol.com/glossary-mmp13): MMP13 (matrix metalloproteinase 13) is an enzyme made by cartilage cells that cuts type II collagen, the main fibre of cartilage. Higher MMP13 is one of the hallmarks of cartilage cells shifting into a breakdown state.
- [N-acetylcysteine (NAC)](https://gluthanol.com/glossary-n-acetylcysteine-nac): N-acetylcysteine (NAC) is a form of the amino acid cysteine with an acetyl group attached, which cells can use as a source of cysteine to make glutathione. It is widely used in research as a glutathione precursor and antioxidant.
- [Nrf2](https://gluthanol.com/glossary-nrf2): Nrf2 is a transcription factor, a protein that switches genes on, that acts as the master switch for a cell's antioxidant defences, including the enzymes that make glutathione.
- [Osteoarthritis](https://gluthanol.com/glossary-osteoarthritis): Osteoarthritis is the most common joint disease, in which joint cartilage breaks down over time along with changes in the bone and other joint tissues. It is a leading cause of chronic disability in older people.
- [Oxidative stress](https://gluthanol.com/glossary-oxidative-stress): Oxidative stress is the state in which a cell's production of reactive oxygen species outpaces its antioxidant defences, so oxidants start damaging molecules and disturbing the cell's signalling.
- [Oxidised glutathione (GSSG)](https://gluthanol.com/glossary-oxidised-glutathione-gssg): Oxidised glutathione (GSSG) is the used form of glutathione: two glutathione molecules joined through their sulphur atoms after neutralising an oxidant. The enzyme glutathione reductase turns it back into two molecules of working GSH.
- [Peroxiredoxin](https://gluthanol.com/glossary-peroxiredoxin): Peroxiredoxins are a family of antioxidant enzymes that remove hydrogen peroxide and help regulate the cell's redox signals. Too much oxidant can over-oxidise them and switch them off.
- [Reactive oxygen species](https://gluthanol.com/glossary-reactive-oxygen-species): Reactive oxygen species (ROS) are oxygen-containing molecules, such as superoxide and hydrogen peroxide, that react readily with fats, proteins and DNA. Cells make them as by-products of normal metabolism and use some of them as signals.
- [Reduced glutathione (GSH)](https://gluthanol.com/glossary-reduced-glutathione-gsh): Reduced glutathione (GSH) is the working, single-molecule form of glutathione, with a free thiol group on its cysteine that can neutralise oxidants. Once it has done that job it becomes oxidised glutathione (GSSG).
- [SOX9](https://gluthanol.com/glossary-sox9): SOX9 is the master transcription factor of cartilage cells, the protein that keeps a chondrocyte working as a chondrocyte by switching on cartilage genes. Falling SOX9 is a sign that cartilage cells are drifting away from their normal role.
- [Synovial fluid](https://gluthanol.com/glossary-synovial-fluid): Synovial fluid is the thick, slippery fluid inside a joint capsule that lubricates the cartilage surfaces. Because cartilage has no blood supply, it is also the route by which nutrients reach the cartilage cells.
- [Type II collagen](https://gluthanol.com/glossary-type-ii-collagen): Type II collagen is the main collagen of articular cartilage, forming the fibre network that gives the tissue its strength. It is made by chondrocytes, the cartilage cells.