Up to 24 patients with moderate to severe pneumonia - which develops in serious cases of Covid-19 - will be recruited to take part in the trial which is expected to be finished before the end of the year.
The treatment would prevent the progression of pneumonia.
"It's not going to cure coronavirus and it's not like a vaccine that will prevent it, but it's particularly designed for patients who progress from the very mild form [of the virus] to the very dangerous form that causes people to have to go to hospital," study co-leader Professor Graham Jenkin, Monash University, told news.com.au.
Jenkin said UK Prime Minister Boris Johnson was a good example of this kind of case.
Johnson had to go to hospital after his condition worsened.
Jenkin said if patients were treated as soon as they arrived at hospital, before their condition progressed to Acute Respiratory Distress Syndrome (ARDS), it could prevent deaths.
ARDS develops from cytokine storm syndrome, an over-reaction of the body's immune system to the virus caused by localised over production of inflammatory factors.
Study co-leader Atul Malhotra, a clinician scientist at Monash Health and Monash University, said when the virus entered the lungs, it triggered the body's immune response to attack the virus, resulting in localised inflammation.
He said increasing evidence suggested that a subgroup of patients with severe Covid-19 may develop cytokine storm syndrome.
"The localised inflammatory response can result in hyper-inflammation, causing serious harm to affected organs, resulting in multi-organ failure and, if untreated, the cytokine storm syndrome, which is often fatal," Malhotra said.
"Our aim in this Covid-19 trial is to prevent the hyper-immune reaction leading to a cytokine storm before it progresses to Acute Respiratory Distress Syndrome."
The trial — involving clinicians and researchers from Monash Health, Monash University and industry partner Cell Care Australia — is the first in the world to use cord blood-derived cells for Covid-19 related pneumonia.
Malhotra said umbilical cord blood had been shown to be anti-inflammatory, immunosuppressive and lodge in the lung, the primary site of the infection that causes Covid-19.
The cells are sourced from cryogenically frozen donated umbilical cord blood.
Jenkin said the breakthrough had been in increasing the number of cells in the lab.
He said if a trial was successful, it would lead to prevention of progression to ARDS, faster resolution of symptoms and earlier discharge from hospital.
While Covid-19 pneumonia is slightly different to the usual kind, he said hopefully the treatment could be used for that as well.
He hopes it can eventually be used to treat newborn babies with brain damage.
