Systemic stem cell research means giving cells into the bloodstream, usually by intravenous infusion, rather than injecting them into one joint or muscle. The studies below ask three questions: whether infusion is safe, where the cells go once they arrive, and what the trials measured in each condition. The research on route is still unsettled [6]. A systematic review of 29 clinical trials found that 13 used intravenous delivery, and it named gaps in dose and route that remain open [6]. This guide describes that research only. GIOSTAR's own intravenous protocol is described on its stem cell IV page, which is a service page and not part of this research summary.
Safety across randomized trials
A safety review pooled 42 randomized trials of umbilical cord mesenchymal cells, with 2,280 patients [1]. It found an increased risk of fever (relative risk 2.34, 95% confidence interval 1.02 to 5.35), and no other prespecified adverse event showed a signal of harm [1]. A 2023 meta-analysis of 13 randomized trials in acute respiratory distress syndrome found no significant difference in adverse events between cell and control groups [3]. A 2023 review of four randomized trials in ischemic stroke, with 97 patients, found no significant difference in mortality or stroke recurrence [4].
Where the cells go
Lung trapping is a recognized problem for intravenous delivery [6]. A 2025 study tracked umbilical cord cells in mice after injection, using four methods, and reported that each method had strengths and weaknesses [12]. Positron emission tomography tracked cells for a long time, but tracer shedding and dead cells complicated the results, and bioluminescence gave specific signal that faded quickly [12]. A 2024 study found that surface modification reduced cell adhesion in a laboratory test by up to 43.5 percent but did not significantly reduce lung trapping in animals [13]. Culturing the cells as three-dimensional spheroids made them pass through the lungs more easily and reach the liver [13].
Efficacy by condition
- Acute respiratory distress syndrome. A 2025 meta-analysis of 48 studies (31 in the pooled analysis) with 1,773 patients found that cells, or the vesicles and secretions they release, were associated with fewer deaths from all causes in the first month (relative risk 0.74, 95% confidence interval 0.62 to 0.89) [2]. The same pooled group included secretome products, so the result is not a result for cells alone [2].
- Ischemic stroke. A 2025 meta-analysis of 17 studies found that non-intravenous route groups improved more on several functional scores at 6 and 12 months, and that mortality fell in both route groups [5]. The non-intravenous groups showed greater gains at 6 and 12 months, and adverse events did not differ significantly from control [5].
- Respiratory distress from COVID-19. The extended follow-up of the STROMA-CoV-2 trial enrolled 47 patients [7]. Its main trial had not identified significant efficacy, and this extension reports safety at 6 and 12 months [7].
- Multiple sclerosis. A randomized phase 2 trial tested a single intravenous infusion of autologous bone marrow cells [8]. The publisher has issued corrections to this report, so this guide does not quote its results.
- Parkinson's disease. A phase 2 randomized, placebo-controlled trial with 45 enrolled people tested repeated intravenous allogeneic infusions [9]. At week 62, a larger share of people in the three-infusion arm reached a 5-point improvement on the motor scale than in the placebo arm (mean difference 5.0 percentage points, posterior probability 93.7%) [9]. The two-infusion arm did worse than placebo, and some improvement appeared in every arm [9].
Registered trials
Two more registered intravenous studies cited here, besides the Parkinson's trial above, are listed on ClinicalTrials.gov [10][11]. One recruiting trial in septic shock plans 296 participants [10]. One frailty trial, active and no longer recruiting, lists 66 participants and has no posted results [11].
How to read an intravenous study
- The dose and schedule. Repeated infusions produced different results in the same condition [9].
- The cell source and product.
- The control. Placebo, usual care and active comparators answer different questions.
Where to find the studies
Search intravenous stem cell studies on ClinicalTrials.gov for registered designs and status. Search intravenous mesenchymal stem cell reviews on PubMed for published reviews. The neuropathy guide covers stem cell research and peripheral neuropathy and the knee guide covers stem cell research and the knee.
Regulatory Status
A 2026 review of FDA regulation of biologics examines how that oversight applies to stem cell products [14]. Our stem cell therapy is not approved by the FDA.
