Stem cell treatments for oropharyngeal dysphagia: Rationale, benefits, and challenges

Table 1 Recent advances in targeted stem cell therapy for oropharyngeal dysphagia

Ref.	Sample, n	Main findings
Tongue dysfunction
Kim et al[20] (2003)	30 rats	Myoblast-containing collagen hydrogel group demonstrated statistically significant increase in tongue weight and desmin-positive cells at the surgery site
Bunaprasert et al[21] (2003)	60 rats	Myoblast-containing gel group showed interdigitating new muscle and neuroma-like fibers, with less scar tissue formation
Luxameechanporn et al[22] (2006)	12 rats	Six weeks post surgery, myoblasts persisted in all 12 rats, had limited migration, showed less scar contracture, and had increased muscle diameter
Kuhn et al[23] (2017)	16 mice	Human MDSCs injected into a hemiglossectomy model survived to the endpoint demonstrating 132% bioluminescence compared to 15% in control groups, and exhibited the greatest weight gain among all groups
Vahabzadeh et al[24] (2018)	18 athymic rats	Three weeks post MSC injection following partial glossectomy, rats which received MSC treatment were found to have reduced x-sectional scar burden and pathologic scores for inflammation and fibrosis
Plowman et al[25] (2014)	1 ovine	MDSCs survived 2 mo following bilateral hypoglossal nerve crush, and demonstrated increased muscle fiber diameter, 27% increase in maximal tongue force, and 54% increase in base of tongue pressure compared to pre cell injection
Xerostomia
Lombaert et al[28] (2008)	13 mice	Salivary glands cultured in vitro then injected into irradiated glands demonstrated increased surface area of acinar cells and 42% increase in saliva production compared to untreated irradiated group
Nanduri et al[29] (2013)	15 mice	54.59% increase in salivary gland function following intraglandular injection of salisphere-derived c-kit positive cells in irradiated mice, compared to 21.5% in untreated mice
Ikeura et al[32] (2016)		Salivary gland basal and ductal cells isolated form submandibular glands were successfully cultured for over 80 passages while maintaining their proliferative ability and morphology
Dai et al[33] (2019)		ADSCs demonstrated the ability to differentiate into acinar-like epithelium capable of secreting α-amylase and expressing AQP-5
Grønhøj et al[35] (2018)	30 patients	Patients who received ADSC injection in submandibular glands demonstrated 50% improved unstimulated salivary flow rates at four months, markedly decreased symptom reports, increase in serous glands, and decreased fibrosis and fatty deposit on biopsies
Cricopharyngeal dysfunction
Périé et al[41] (2014)	12 patients	6/12 patients by videoendoscopy but only 2/12 patients by videofluoroscopy demonstrated improved UES function following myoblast injection and CP myotomy. Swallowing function improved in all patients subjectively and mean swallowing time decreased in all patients from 23.7 s to 10.2 s

MDSC: Muscle-derived stem cell; MSC: Mesenchymal stem cell; ADSC: Adipose tissue-derived stem cells; UES: Upper esophageal sphincter; CP: Cricopharyngeus muscle.