Plant-Derived Vesicle-like Nanoparticles: The Next-Generation Drug Delivery Nanoplatforms

Round 1

Reviewer 1 Report

This would be a nice review of plant-derived extracellular vesicles (EVs) and their potential application to mammals. Overall, the information in this paper seems to be an accumulation of some information from different articles. I am not an expert on plant-derived EVs, and the thoroughness of the citations should be asked to other experts. But what new insight this review brings is not clear.

Major comments:

1. The manuscript summarizes the potential of PDVLNs as a nano platform for next-generation drug delivery systems. However, the authors did not mention the characteristic features of PDVLNs. For instance, how they are isolated from plants, which plant parts are abundant in PDVLNs, the size of PDVLNs, yield value or yield percentage of PDVLNs, difference between PDVLNs and mammalian exosomes, etc. Before they start any conversation on the therapeutic application of PDVLNs, they should characterize the PDVLNs.

2. While mentioning the composition of PDVLNs, the authors should make a table mentioning the plant name, secreted lipid type of PDVLNs, impact on disease, animal studies or clinical trials (if available), etc. 

3. Regarding the administration routes, a separate table should mention the therapeutic efficacy, bioavailability, tolerance, stability, and side effects of PDVLNs in different routes.

Biogenesis: The consensus in the EV research is that the heterogeneity of EVs is one the biggest challenges in the field. The manuscript mentions that the biogenesis of plant derived EV can be categorized into three pathways, how do these three pathways differ from each other, and how can it be characterized? Since the protein and lipid profile profiles of EVs are influenced by the origin, a more detailed underlying cellular mechanism, the cargo sorting processes and methods to characterize these pathways would be beneficial.

The authors mentioned that three pathways are involved in the biogenesis of PDVLNs. However, they should introduce these pathways briefly, i.e., how they function and the correlation of PDVLNs with these pathways.

4. In point 3.1. Lipids, the argument about lipid composition in which PA can stimulate the mTOR pathway, please relate this argument in the context of PDLVN.

Cholesterol is not in the plant, and thus, it is a very natural outcome that the plant-derived EVs do not have cholesterol. The lines 110 -111 should be corrected.

5. In point 3.2. Proteins: The manuscript compares different levels and types of protein content. For the protein level comparison, what is the basis of these comparisons, what is considered lower and higher? Please be more definitive in this description.

For the type of protein found of PDVLN, the manuscript mentions peripheral membrane, transmembrane and intracellular proteins but did not provide examples of what these proteins are. This information is crucial in characterizing PDVLNs.

Line 152: What is CD98 protein? Please briefly introduce the protein in this discussion.

In point 3.3 Nucleic acids, line 164-168, the paragraph implies that the delivery of PDV to recipient cells is enabled by the RNAs found in them, please discuss further and provide citation for this claim. Or please review the sentence structure to avoid misunderstanding.

In point 4.2 IV injection, the biodistribution of PDVLNs through different administration routes is indeed interesting. Elaboration on the subject and its compatibility with an aim of a treatment would be a good point of discussion. 

6. In point 5. Advantages of PDVLNs,

-Line 308, what is the antioxidant capacity definition here? Please elaborate.

-Line 309, What is the ‘distinct pattern’ meant in the comparison between the strawberry PDVLNs and juice here, please elaborate. 

7. In the advantage-disadvantage section, they only mentioned some common good and bad things, which are present in many other existing drugs as well. What exclusive advantage do PDVLNs present is not mentioned. Also, there is no discussion of how the disadvantages can be managed.

8. In Point 6. The Application of PDVLNs,

-Line 336-338, what is the surface protein proposed or candidate from this statement if there’s any? Please provide a citation to this statement.

9. They should also include what the authors think about the potential of PDVLNs based on current evidence and possible ways of combating the challenges when it comes to considering PDVLNs as drug-like molecules.

Minor points

Some common words were typed with the capital first letters: ‘Scientists’ (line 37), ‘Vacuoles’(line 84), ‘Biogenesis’(line 85),…

Some abbreviation words were used without further explanation: ‘PDENS’ (line 75), ‘PA’ (line 114,115,119), ‘MDEs’ (line 206,207,219).

In Figure 1, there is a blank space (red circle) between the peripheral membrane protein and cell membrane.

In Figure 2, one transmembrane protein (red circle) is at the wrong position.

There are many statements that require at least one, if not more, citations to make such claims. Here is the list:

Line: 56 - 60: “Due to the natural biochemicals of the original plant, Plant-derived vesicle-like nanoparticles (PDVLNs) have a pronounced favorable therapeutic effect, which has been demonstrated in numerous disease models. Moreover, a fair portion of them have already involved in developing novel drugs.”

Line 78 & 79: “Among these pathways, the MVBs pathway is the most commonly reported.”

Line 221 - 222: “Conversely, PDVLNs present highly resistant to digestive enzymes including gastric pepsin, intestinal pancreatin, and bile extract solutions.”

Line 267 & 268: “The good news is that there have been several breakthroughs and the translation of PDVLNs from bench to bedside has been on the way.”

Line 288-290: “The fascinating biocompatibility of PDVLNs is also valuable. Many studies reported that there was no significant effect on the physiological and biochemical parameters of experimental animals.”

Line 296-299: “In one study, the placenta did not show any detection of fluorescent signal after grapefruit-derived PDVLNs were injected into pregnant mice, paving the way for potential use of PDVLNs in pregnant women for delivering drugs in the future.”

see above

Author Response

A point-by-point response to the reviewer’s comments can be found in the attached Word.

Author Response File: Author Response.pdf

Reviewer 2 Report

The review manuscript by Wang et al. with a title “Plant-derived Vesicle-like Nanoparticles: Next-generation Drug-Delivery Nanoplatforms” provides an overview of the current literature on plant-derived vesicle-like nanoparticles (PDVLNs). After short introduction, the authors describe biogenesis of PDVLNs, composition of PDVLNs (lipids, proteins, nucleic acids), administration routes of PDVLNs, advantages of PDVLNs, the application of PDVLNs, conclusions and future directions. The review provides some new information, but it is not clear what its focus is. The title’s focus on “next-generation drug delivery nanoplatforms” is not very clear and should be improved. There are several similar reviews in the literature. I strongly recommend focusing clearly on drug delivery. 

Some English corrections are required.

No information is provided regarding methods to isolate PDVLN. The only statements is that the “mammalian exosomes need complex preparation steps” are the “plant exosomes preparation steps less complex”? Please add a short paragraph describing the methods of isolation. It would also make sense to add “isolation” to Table 1.

It would be good to have an explanation of the various nomenclatures used in the review. The authors use “EV, extracellular vesicles”, “exosomes”, “plant-derived vesicle-like nanoparticles, PDVLN”.

It is not always clear what type of studies the authors cite e.g. whether the tests were carried out on animals, in vitro on mammalian cells, or in clinical studies in humans. Please try to clarify for each example cited.

should be corrected moderately

Author Response

A point-by-point response to the reviewer’s comments can be found in the attached Word.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

 I think they have improved the manuscript and addressed the comments largely.  The flow of the manuscript is better in this edited version, with more detailed elaboration and evidence on their key points being provided. They did a good summary and discussion of current understanding in the field, which served its purpose for a review paper.

required

Reviewer 2 Report

The authors improved the manuscript according to the reviewer’s comments. I have no more concerns.

has been improved