An incredible 21-year-old who inspired thousands across the world in her fight against Cystic Fibrosis has died.

Brave Roisín Kelleher-O'Callaghan, of Whitstable Road in Faversham, raised thousands of pounds to be the first person in the UK to receive stem-cell treatment for the lung disease, but despite a period of improved health and starting university in September, she passed away on Tuesday.

The former Ethelbert Road and Queen Elizabeth’s Grammar School pupil had collected more than 5,000 signatures in a petition to bring the treatment, which is only available in the Dominican Republic, to the UK.

The Breathe Hope for Roisín campaign, which launched with the help of Kent Online in 2014 and helped to raise more than £70,000 for her trip to the Dominican, has been followed by the eyes of people around the globe, all of whom have been left heartbroken this week.

The campaign Facebook page has more than 5,000 followers, each one of them inspired by Roisín's determination against all odds.

Within the Cystic Fibrosis community, she had become a symbol of hope after the stem-cell treatment brought Roisín months of improved health and gave her the opportunity to study psychology at university and celebrate her 21st birthday.

Roisín leaves behind her mother Anntoinette, brother Cian, Brendan and Chris and hundreds of family and friends.

Anntoinette, who poignantly was a stem-cell match for her daughter during her treatment, told KentOnline today: "I feel so privileged to have been Roisín's mum.

"Every day we would learn something from her.

"She was the most amazing, perfect human being" - Roisin's mum Anntoinette

"If you were ever upset or angry, she always had that compassion you needed and she put everything into perspective for you.

"Despite what she was going through, she always thought about others before herself and cared so much about what others were going through.

"She never said 'why me?' She never felt sorry for herself and she never once complained, even until the end.

"She was the most amazing, perfect human being. A beautiful soul.

"Roisín brought such a sense of humanity and love to everyone. She had an impact on everyone she met."

Roisín still achieved two Bs during her AS-Levels despite having to skip so much time at school because of her illness, and was delighted to be well enough to start university.

She took a huge interest in politics, frustrated by social injustice and loved reading and researching the world around her.

From a young age she wanted to open an animal rescue centre and loved looking after animals - from slow worms to rabbits she found in the garden - and adored her two dogs Archie and Heidi and the family cats.

Roisín was also a talented crocheter and had "an incredible sense of humour".

Diagnosed with Cystic Fibrosis at 16 weeks old and pulmonary hypertension in 2014, (just one other person in the UK has both conditions), every day for Roisín has been an hourly catalogue of medication and IVs, hundreds of hospital appointments and the prospect of a lung transplant constantly on the cards.

Anntoinette says that there were many times throughout her life when doctors told Roisín that she was going to die, but she powered through time and time again.

Anntoinette added: "This time was very different and we knew it was different because Roisín was so at peace.

"She wasn't scared, she was just worried about me and her brother Cian, and that says everything about Roisín - even then, she was more concerned about others and was always thanking or apologising to the doctors and nurses. They thought she was incredible.

"A lot of people say she has lost her battle but it was not a fight for Roisín. It was about wanting to be alive.

"She blows my mind. So many people have told me they are heartbroken. My heart has shattered. Empty does not even begin to cover it."

When the family discovered the stem-cell treatment and launched the Breathe Hope for Roisín campaign, it sparked a rare glimmer of hope.

Thousands joined the drive to turn that hope into reality with schools, businesses, community groups and individuals throwing themselves behind the fundraising.

There were sponsored walks, fetes, schools held fundraising events and thousands donated through the Just Giving page - the money flooded in within months.

When she returned from America, Roisín told KentOnline she had taken her “first proper deep breath in forever” and it was “nothing short of a miracle”.

Anntoinette said: “The treatment meant that Roisín was off of IVs for seven months - that's the longest time she has ever been off them.

"Another woman who had the treatment after Roisín is doing really well and she says that Roisín saved her life.

"The Cystic Fibrosis Trust still rejects the treatment but we hope that one day that will change.

"The word that keeps coming up is 'inspirational'. She really was. She is our angel and I cannot even begin to imagine what our lives will be like without Roisín."

After suffering from respiratory failure towards the end of last year - which Anntoinette believes she never would have survived if it was not for the stem-cells - Roisín's health had been up and down but she had spent the last few months in King's College Hospital in London after a number of complications.

Requim Mass will be held on Thursday, August 18 at Our Lady of Mount Carmel Catholic Church in Faversham at 9.30am before a service at the Garden of England Crematorium in Bobbing, Sittingbourne at 11am.

Roisín wanted people to wear something bright, colourful, positive and purple and asked for a "celebration".

In her own words, she wrote: "I would like the emphasis to be on life, love and family, more of a celebration than sadness."

Roisín has expressed that in lieu of flowers she would like donations to be made to Happy Endings Animal Rescue centre in Faversham.